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The Fungus-Growing Ants of North America. 



By William Morton Wheeler. 



AUTHOR'S EDITION, extracted from BULLETIN 

OF THE 

Hmerican flDuseum of.lRatural History, 

Vol. XXIII, Article XXXI, pp. 669-807. 
New York, September SO,- 1907. 



59.57, 96 A: 15.3 

Article XXXI.— THE FUNGUS-GROWING ANTS OF NORTH 

AMERICA. 

By William Morton Wheeler. 

Plates XLIX-LIII. 

Introduction. 

Among the multitudinous activities of insects, none are more marvellous 
than the fungus-growing and fungus-eating habits of the Attiine ants. Not 
only are these habits of interest as a most unusual specialization in diet — 
for all ants were originally and many are still exclusively entomophagous — 
but the successful cultivation of such delicate plants as fungi presupposes 
an astonishing range and complexity of adaptation even for these very 
plastic insects. This statement will be endorsed by those who have tried 
to obtain pure cultures of fungi either in the hot-house or the laboratory. 
Besides the selection of proper culture media and the accurate regulation - 
of tetaperature and moisture, exquisite precautions have to be taken to 
exclude the germs of alien species. The Attii are able to achieve all this and, 
what is equally remarkable, at least two other groups of insects, namely, cer- 
tain Old World termites and the "ambrosia beetles" (Tomicine Scolytidee) 
of both hemispheres, have independently developed analogous habits. 

The fungus-growing ants all belong to a single Myrmicine tribe, the 
Attii, and all the species of this tribe are fungus-growers. They are, more- 
over, confined almost exclusively to tropical and subtropical America, only 
a single species being known to range as far north as New Jersey. And 
since a few others occur as far south as Argentina, we may say that the 
geographical distribution of the tribe extends from 40° north to 40° south of 
the equator. About one hundred species, subspecies and varieties of Attii 
have been described and have been distributed among various genera and 
subgenera, as follows: 

Genus Atta Fabricius. 

Subgenus Atta sensu stricto, including: A. cephahtes L. with the vars. 
lutea Forel, opacd Forel, polita Emery and integrior Forel; sexdens L., with 
the subsp. voUenweideri Forel; Icevigata F. Smith; columhica Gu6rin; 
insularis Gu6rin; fervens Drury; texana Buckley. 

Subgenus Mcellerius Forel, including: M. heyeri Forel; striata Roger; 

669 



670 Bulletin American Museum of Natural History. [Vol. XXIII, 

silvestrii Emery; halzani Emery; landotti Forel; versicolor Pergande with 
the subsp. chisosensis Wheeler. 

Subgenus Acromyrmex Mayr, including: A^ subterranea Forel; lobi- 
cornis Emery and its var. ferruginea Emery; lundi Guerin; ambigua Emery; 
fuhescens Emery with the subsp. bonariensis Emery and decolor Emery; 
emilii Forel; octospinosa Reich with the var. echinatior Forel; mwlleri 
Forel with the vars. panamensis Forel and meinerli Forel, and the subsp. 
modesta Forel with the var. andicola Forel; coronata Forel; mesonotalis 
Emery; discigera Mayr; muticinoda Forel with the var. homalops Emery; 
nigra F. Smith; aspersa F. Smith with the var. rugosa F. Smith; laticeps 
Emery; bolivlensis Emery; iheringi Emery. 

Subgenus Trachymyrmex Forel, including: T. urichi Forel with the 
subsp. fusca Emery; pruinosa Emery; septentrionalis McCook with the var. 
obscurior Wheeler; turrifex Wheeler; arizofiensis Wheeler; jamaicensis 
Em. Andre; saussureiYorel; squamulifera'Exnevy; farinosa HmcTy. 

Subgenus Mycetosoritis Wheeler, including: M. hartmanni Wheeler; 
aspera Mayr. 

Subgenus Mycocepurus Forel, including: M. goldii Forel, smithi Forel 
with the vars. toUeca Wheeler and borinquenensis Wheeler. 



Genus Cyphomyrmex Mayr. 

C. rimosus Spinola with the subsp. minutus Mayr, salvini Forel, 
dentatus Forel, transversus'ETxieTY and olindanus Forel, and the vars. major 
Forel, ]usca Emery and comalensis Wheeler; parallelus Emery; oKtor Forel; 
auritus Mayr; morschi Emery; simplex Emery; strigatus Mayr; wheeleri 
Forel; kirbyi Mayr; flavidus Pergande; championi Forel; foxi Ern. Andr6; 
bigibbosus Emery. 

Genus Myrmicocrypta F. Smith. 

M. squamosa F. Smith; dilacerta Forel with the suhs\) : cornuta Forel; 
subnitida Forel; godma/ni Forel; fcn'tom Wheeler. 

Genus Sericomyrmex Mayr. 
S. opacus Mayr; astecus Forel; saussurei Emery. 



1907.] Wheeler, Fungus-growing Ants of North America. 671 

Genus Apterostigma Mayr. 

A. pilosumMajr; scuteUare¥ovel; viosUeriVoTel; wasmanni Forel; urichi 
Forel; mayri Forel; collare Emery; robustum Emery. . v 

The various subgenera included under Atta sensu lato will probably be 
raised eventually to generic rank. The subgenus Atta comprises the leaf- 
cutting or parasol ants, the largest and most powerful species of the tribe, 
living in great colonies and inhabiting the territory between 30° north and 
30° south of the equator. The workers are highly polymorphic and much 
smaller than the males and females. The colonies of the species of Mcellerius 
and Acromyrmex are much less populous, and the workers, though variable 
in size, do not exhibit such marked polymorphism as those of Atta s. str. 
In Trachymyrmex and the remaining subgenera the workers are mono- 
morphic and but little smaller than the males and females, and the colonies 
are even feebler than those of Acromyrmex. Mycetosoritis and Mycocejmrus 
are in certain respects transitional to the genera Cyphomyrmex and Myr- 
micocrypta, and species of the last show affinities with Sericomyrmex. Apte- 
rostigma is very aberrant, resembling in form certain Myrmicines of the 
subgenera Aphcenogaster and Ischrwmyrmex. The workers of Atta are 
covered with stiff, erect or suberect, hooked or curved hairs, and the sur- 
face of the body is tuberculate or spinose. In Cyphomyrmex the body is 
smoother and covered with short, appressed, scale-like hairs. In Serico- 
myrmex audi Apterostigma the hairs are soft, flexuous and very abundant. 
With few exceptions all the Attii have the surface of the body opaque and of 
a ferruginous, brown or blackish color. All the species, moreover, though 
very powerful and able to make surprisingly extensive excavations in the 
soil, are very slow and stolid in their movements. The sting of the workers 
is vestigial, but in the larger species the sharp jaws may be used as most 
' efficient organs of defence. The smaller species are extremely timid and 
when roughly handled "feign death" like Curculionid beetles. In all the 
species the hard, rough or spinose integument must afford efficient protection 
from alien ants and other enemies. 

Owing to. the labors of Forel, Emery and Mayr our knowledge of the 
taxonomy of the Attii is probably as satisfactory as that of any other groups 
of exotic ants. As much cannot, however, be said of our knowledge of the 
habits. Since all the Attii live in intimate symbiosis with fungi, a complete 
study of the habits of these insects requires the diligent cooperation of the 
entomologist and botanist. Hitherto the botanists, notably Alfred Moeller 
and Jakob Huber, have contributed the most accurate observations. As 
neither the botanists nor the entomologists of North America have shown 
any very serious interest in the Attii, I need not apologize for publishing the 



■672 Bulletin American Museum of Natural History. [Vol. XXIII, 

following pages. Though these contribute little towards a solution of many 
of the outstanding problems, they nevertheless contain a number of observa- 
tions that may be of permanent interest and value. My attention was first 
attracted to these insects several years ago while I was sojourning in Texas. 
It was, in fact, the sight of a leaf-bearing file of Atta texana, moving along 
the bank of Barton Creek near Austin, one sultry afternoon in September, 
' that first kindled my interest in the habits of ants. I postponed publishing 
my notes on this and other species, hoping to have an opportunity to study 
a greater number of forms in the heart of the tropics, but as there is no 
immediate prospect of my being able to continue the work in these regions, 
I have decided to publish my observations as they stand. The present 
article is divided into four parts, namely, a r6sum6 of the writings of previous 
students of the Attii, a taxpnomic revision of the known North American 
members of the group, including a few from Mexico and the West Indies, 
an account of my own observations on these same forms, and a general 
consideration of some of the inain problems involved in the study of the 
fungus-growing instincts not only in the Attii but also in the termites and 
.ambrosia beetles. 

Part I. Histoeical. 

The large leaf -cutting ants of the genus Atta s. str. are such conspicuous, 
widely distributed, and destructive insects in tropical America that they 
must have been only too familiar to the indigenes and the early settlers in 
those regions. That these ants figured prominently in the Indian mytholo- 
gies is indicated by a passage in the Popul Vuh, a collection of Guatemalan 
t:raditions to which my friend Mr. F. Bandelier has called my attention.' 
This collection was made by Dominican friars, probably during the middle 
■or latter half of the sixteenth century. The following myth refers to the 
larger species of Atta which are known to collect the petals and whole flowers 
as well as the leaves of plants. The mythical young men, Hunahpu and 
Xbalanqu6, had been taken in ambush and required by their captors, Hun- 
Cam^ and Vukub-Cam6 to fetch four vases of certain flowers as a test, and 
to forfeit their lives in case of failure. "Thus they stayed in the House of 
the Lances during the night, when they called on all the ants: "Cutting 
ants and zampopos,' come and together fetch the flowers designated by 
the princes." 

• Popul Vuh. Livre SacrS et les Mytlies de 1' Antiquity Araericaine avec les Livres HSroiques 
et Histonques des Quiches, par L' Abb^ Brasseur de Bourbour. Paris, Aug. Durand, 1861. 

2 Zanic is the generic name of the ant. Cheguen-zanic is a large ant which goes about at 
night cutting the stems of vegetables and tender flowers, as if with scissors. Its name among 
the Hispano-Guateraalan peoples is zampopo. (Commentator's note.) 



1907.] Wheeler, Fungus-r/roiving Ants of North America. 673 

"Very well," they replied. Then all the ants set out to fetch the flowers 
of the garden of Hun-Came and Vukub-Came. These had apprised the 
guardians of the flowers of Xibalba in advance: "As to you, give heed to 
our flowers; do not let these two young men, whom we have taken in ambush, 
carry off any of them. Where else could they go .to get those we have desig- 
nated? There are none elsewhere. Watch closely therefore' throughout 
the night."— "It is well," they rephed. 

"But the sentinels of the garden heard nothing of what was going on. 
In vain they went about, walking on their legs, among the branches of the 
trees of the garden, and repeating the same song. "Xpurpurek, Xpurpurek! 
sang one. — "Puhuyu, puhuyu!" repeated the other. 

"Puhuyu was the name of the two sentinels of the plantations of Hun- 
Cam6 and Vukub-Came. But they did not notice the ants stealing away 
what had been committed to their charge, going and coming in innumerable 
hordes, cutting down the flower beds, moving along with the flowers which 
they bore away in their jaws above the trees, while under the trees the 
flowers exhaled a sweet odor. 

"Meanwhile the sentinels kept shouting with all their might, without 
noticing the teeth that were sawing at their tails and wings. ^ There was a 
harvest of flowers mown down by their jaws and borne all odoriferous by, 
their jaws into the House of the Lances. 

"Very soon the four vases were filled with flowers, and they were quite 
full when the day dawned. Soon thereafter the messengers Came to seek 
them. " Let them come," said the King, "and let them bring forthwith 
what we have demanded," said they to the young men. 

"Very well," said they. Thereupon they proceeded to fetch the four 
vases of flowers. Then, having presented themselves before the king and 
the princes, these took the flowers whose sight it was a pleasure (to behold). 
Thus were those of Xibalba tricked. ' 

"It was the ants alone who had been dispatched by the young men, and 
who in a single night had carried away all the flowers and placed them in 
the vases. At this sight all the (princes) of Xibalba changed color and their 
faces paled on account of the flowers. 

"Then they sent the men to seek the guardians of the flowers: "Why 
did you permit our flowers to be stolen. Are these not our own flowers 
which we here behold?" said they to the guardians. — "We did not notice 
anj'thing, my lord. They did not even spare our tails," they replied. Then 
they split the lips of the guardians, to punish them for having permitted the 
theft of that which was committed to their charge. 

1 The commentator states that he is unable to understand this allusion. The guardians 
are evidently conceived as birds, as shown by the above reference to tbeir "walking on their 
legs," although this is not clearly stated till the end of the passage. 



674 Bulletin American Museum of Natural History. [Vol. XXIII; 

"It was in this manner that Hun-Cam6 and Vukub-Came were van- 
quished by Hunahpu and Xbalanque, and this was the beginning of their 
labors. Thenceforth, too, the Purpueks had their mouths cleft, and cleft 
they are to this day." '■ 

I am also indebted to Mr. Bandelier for the following extracts from the 
early historians of the Conquest. Gonzalo Fernandez de Oviedo y Valdes 
in his 'Historia de las Indias' (1535) gives an account of the pernicious ants 
and termites of Espanola (Santo Pomingo). Among the former are certain 
species "which do very great damage throughout the island, in the planta- 
tions, destroying and burning up the cane a;nd oranges and other useful 
plants." These ants must have been the large species of Atta, probably 
A. insulafis, which does great damage to plantations also in the adjacent 
island of Cuba. 

P. Bernabe Cobo, in his 'Historia de Neuvo Mundo' (1653) also describes 
a number of noxious ants in Santo Domingo. He says: "There is another 
kind of large ants which the Chiriquan, Indians call Iczau, and it is these 
which eat the trees and whose young, w'hen newly hatched, are called Icza, 
and are eaten by the Indians." These Iczau are evidently the virgin females 
of Atta. They are a'so eaten by the Brazilian Indians who call them Ifas, 
according to von Ihering (1894). Cobo seems to be the first author to record 
the use of the heads of Atta soldiers by the Indians for surgical purposes: 
"They use a certain species of the said ants, because they bite severely, for 
closing Yvounds instead of stitching them with a needle. This is done in the 
following manner : they bring together the skin of the two sides of the wound 
and apply these ants, which bite and hold the two sides or lips together and' 
then they cut off the insects' heads, which remain attached to the wound 
with their mouths or mandibles as firmly closed as they were in life." 

Specimens of the large Atim were, of course, taken to Europe by the 
early travelers. Seba (1734^35) gives a good figure of a soldier of A. 
cephalotes or sexdens. which found its way into his collection. Linn6 de- 
scribed both of these species, and they were also known to- Fabricius and 
Latreille. The latter authors, apparently misled by the accounts of Mile. 
Merian (1771), confounded the habits of these ants with those of the "fourmis 
de visites," ov Ecitons. 

The first naturalist to publish observations on any of the North American 
Attii was Buckley (1860), who studied the habits of Atta.texana at Austin, 
Texas. He was evidently under the impression that this ant eats the leaves, 
berries, etc., which it carries into its nests. He unearthed some of the 



• Here the guardians pass into the domain of fable; they become night birds, the one called' 
Purpuek, the other Piihiiy , which is a species of owl ; at the present time the former is pronounced 
, Parpueli. (Commentator's note.) 



1907.] Wheeler, Fungus-growing Ants oj North America. 675 

nests and describes the "soft grey spongy substance, apparently leaves, 
finely triturated and mixed with an animal secretion," found in the chambers. 
This "animal secretion" was undoubtedly the web of fungus hyphse which 
binds the leaf particles together. 

Bates (1863) in his classical 'Naturalist on the Amazon' gives an excel- 
lent account of Atta cephalotes, one of the ants called "Saubas" by the, 
Brazihans. He described the extensive earthworks of this species, "large 
mounds of earth of a different color from the surrounding soil, which were 
thrown up in the plantations and woods. Some of these were very extensive,- 
being forty yards in circumference, but not more than two feet in height; .... 
The difference in color from the superficial soil of the vicinity is owing to 
their being formed of the subsoil, brought up from a considerable depth.". 
He describes the manner in which the ants cut out pieces of leaves and the 
ensuing damage to cultivated trees and shrubs, and believes that "the leaves 
are used to thatch the domes which cover the entrances to their subterranean 
dwellings, thereby protecting from the- deluging rains the young broods 
in the nests beneath." This erroneous inference was derived from seeing 
the workers "troop up" and cast their pieces of leaves on the hillocks of the 
nest where some of them are often covered by the earth brought up by the 
excavating workers. Bates also records the following observation to show 
the extent of the subterranean burrows of the Sauba: "The Rev. Hamlet 
Clark has related that the Saiiba of Rio de Janeiro, a species closely allied 
to ours, has excavated a tunnel under the bed of the river Parahyba, at a 
place where it is as broad as the Thames at London Bridge. At the Magaory 
rice mills, near Para, these ants once pierced the embankment of a large 
reservoir: the great body of water which it contained escaped before the 
damage could be repaired. In the Botanic Gardens at Para, an enterprising 
French gardener tried all he could think of to extirpate the satlba. With 
this object he made fires over some of the main entrances to their colonies 
and blew the fumes of sulphur down the galleries by means of bellows. I 
saw the smoke issue from a great number of outlets, one of which was 70 
yards distant from the place where the bellows were used." This ant not 
only does great damage to the foliage but also plunders stores of vegetable 
provisions such as farina or mandioca meal in houses at night. Bates 
observed the division of labor among the castes although he did not accurately 
define the soldier, or worker major. From the fact that the latter are often 
seen to be simply stalking about, he concluded that their "enormously large, 
hard and indestructible heads may be of use in protecting them against the 
attacks of insectivorous animals. They would be, in this view, a kind of 
'pieces de resistance,' serving as a foil against onslaughts made on the main 
body of workers." Had Bates undertaken to excavate a large colony of 



676 Bulletin American Mufseum of Natural History. [Vol. XXIII, 

these ants he would soon have discovered that these soldiers have a very 
important function to perform in the active defence of their fellow ants. 

Lincecum in 1867 recorded a number of observations on Atta texana 
which, like his other publications on ants, are a strange jumble of truth and 
fiction. He states rather positively that this ant eats the vegetable sub- 
stances which it collects. "In my observations on the habits of the cutting 
ants, I have not discovered them eating anything besides the foliage of 
various plants. Neither have Lever noticed them carrying anything else 
into their cities. Professor S.'B. Buckley, who is a very close and accurate 
observer [sic !] states that he saw them carrying hackberries (Celtis occi- 
denialis) and that they eat insects, tumble bugs, etc.. . .From the immense 
quantities of leaves collected by them during the autumnal months, which 
are carefully sun-dried and taken into the city, I should feel at a loss to say, 
if they are not intended for winter food, what other use they can put such 
quantities of leaves to; and furthermore, when it is known to be the kind 
of food upon which they subsist." It is interesting to note that while Lince- 
cum overlooked the marvellous fungus-raising habits of Atta texana he 
nevertheless attributed to them certain horticultural interests : ' ' The cutting- 
ants plant seeds of various trees, vines and other plants.. , When they locate 
a city in a bald prairie, which is often the case, where they cannot procure 
the seeds of trees, they cultivate the prickly poppy (Argemone Mexicana) 
the most appropriate plant for their purpose that grows in the prairie. ... 
When the ants locate a city on some sunny point near the timbered lands, 
they do not plant the poppy, but appear to prefer certain trees and vines' 
for shade. For this purpose they plant the seeds of the prairie dogwood 
(Viburnum dentatum), Yopon (Ilex vo-mitmia), Hackberry tree (Celtis 
occidentalis), Gum elastic tree (Bumelia lycioides), the mustang grape (Vitis 
Texana), Cocculus Carolina and occasionally the pricldy ash (Xanthoxyhini 
fraxinum)." While there can be little doubt that various herbs, shrubs, 
or even trees may spring up from the seeds collected and dropped by the 
ants on the soil of their nests, it is absurd to say that such seeds are actually 
planted with an awareness that they will ultimately grow and produce shade. 
Lincecum here repeats the error which he promulgated in regard to the 
harvesting ants of Texas (Pogonomyrmex inolefaciens) . 

Norton (1868) gave a good general description of the Mexican Atta 
fervens, but made no observations on its fungus gardens. 

In 1870 B. R. Townsend studied A . texana id Ausrin, Texas. Concern- 
ing the leaves collected by this ant he says: "These leaves are conveyed 
through these underground passages to their homes and deppsited in one of 
their chambers, and, I presume, they secrete some substance that they put 
with the leaves, for if a handful of the leaves is taken in the hand and squeezed, 



1907.] Wheeler, Fungus-groiuing Ants of North America. 677 

a ball is made very much resembling coarse bees wax, and when dried is as 
hard as dry putty. I judge the leaves by their decay produce a gentle heat, 
or, at least, maintain a uniform temperature whereby the eggs are hatched. 
Formerly it was suggested that these leaves constituted a store of food, ' but 
such is not the case. AVhether they feed upon vegetable or animal food I 
cannot say." 

A new epoch in the study of the fungus growing ants was inaugurated by 
Belt in 1874 in his interesting volume, 'The Naturalist in Nicaragua." He 
was the first to surmise the use to which the leaves, etc., are put by the species 
which he studied (probably A. cephahtes). ' As his work has become rather 
rare, I quote the pertinent passages in full: "Notwithstanding that these 
ants are so common throughout tropical America, and have excited the 
attention of nearly every traveller, there still remains much doubt as to the 
use to which the leaves are put. Some Naturalists have supposed that they 
use them directly as food; others, that they roof their underground nests 
with them. I believe the real use they make of them is as a manure, on 
which grows a minute species of fungus, on which they feed; — that they are, 
in reality, mushroom growers and eaters. This explanation is so extraor- 
dinary and unexpected, that I may be permitted to enter somewhat at length 
on the facts that led me to adopt it. When I first began my warfare against 
the ants that attacked my garden, I dug down deeply into some of their 
nests. In our mining operations we also, on -two occasions, carried our 
excavations from below up through very large formicariums so that all 
their underground workings were exposed to observation. I found their 
nests below to consist of numerous rounded chambers, about as large as a 
man's head, connected together by tunnelled passages leading from one 
chamber to another. Notwithstanding that many columns of the ants 
were continually carrying in the cut leaves, I could never find any quantity 
of these in the burrows, and it was evident that they were used up in some 
way immediately they were brought in. The chambers were always about 
three parts filled with a speckled, brown, flocculent, spongy-looking mass 
of a light and loosely connected substance. Throughout these masses were 
numerous ants belonging to the smallest division of the workers, which do 
not engage in leaf -carrying. • Along with them were pupse and larvse, not 
gathered together, but dispersed, apparently irregularly, throughout the 
flocculent mass. This mass, which I have called the ant -food, proved, on 
examination to be composed of minutely subdivided pieces "of leaves, withered 
to a brown color, and overgrown and lightly connected together by a minute 
white fungus that ramified in every direction throughout it, I not only 
found this fungus in every chamber I opened, but also in the chambers of 
the nest of a distinct species that generally comes out only in the night-time. 



678 Bulletin American Museum of Natural History. [Vol. XXIIl, 

often entering houses and carrying off various farinaceous substances, and 
does not make mounds above its nests, but long winding passages, terminat- 
ing in chambers similar to the common species and always, like them, three 
parts filled with flocculent masses of fungus-covered vegetable matter, 
amongst which are the ant -nurses and immature ants. AVhen a nest is 
disturbed, and the masses of ant-food spread about, the ants are in great 
concern to carry away every morsel of it under shelter again; and some- 
times, when I dug into a nest, I found the next day all the earth thrown 
out filled with little pits that the ants had dug into it to get out the covered 
up food. When they migrate from one part, to another, they also carry 
with them all the ant-food from their old habitations. That they do not 
eat the leaves themselves I convinced myself, for I found near the tenanted 
chambers, deserted ones filled with the refuse particles of leaves that had 
been exhausted as manure for the fungus, and were now left, and served as 
food for larvae of StaphylinirJw and other beetles. 

"These ants do not confine themselves to leaves, but also carry off any 
A'egetable substance that they find suitable for growing fungus on. They 
are very partial to the inside white rind of oranges, and I have also seen 
them cutting up and carrying off the flowers of certain shrubs, the leaves of 
which they have neglected. They are very particular about the ventilation 
of their underground chambers, and have numerous holes leading up to 
the surface from them. These they open out or close up, apparently to 
keep up a regular degree of temperature below. The great care they take 
that the pieces of leaves they carry into the nest should be neither too dry 
nor too damp, is also consistent with the idea that the object is the gro^\'th 
of a' fungus that requires particular conditions of temperature and moisture 
to ensure its vigorous growth. If a sudden shower should come on, the 
ants do not carry the wet pieces into the burrows, but throw them down 
near the entrances. Should the weather clear up again, these pieces are 
picked up when nearly dried, and taken inside; should the rain, however, 
continue, they get sodden down into the ground, and are left there. On 
the contrary, in dry and hot weather, when the leaves would get dried up 
before they could be conveyed to the nest, the ants, when in exposed situa- 
tions, do not go out at all during the hot hours, but bring in their leafy 
burdens in the cool of the day and during the night. As soon as the pieces 
of leaves are carried in they must be cut up by the small class of workers 
into little pieces. I have never seen the smallest class of ants carrying in 
leaves; their duties appear to be inside, cutting them into smaller fragments, 
and nursing the immature ants. I have, however, seen them running out 
along the paths with the others; but instead of helping to carry in the 
burdens, they climb on the top of the pieces which are being carried along 



1907.] Wheeler, Fungus-growing Ants of North America'. 679 

by the middle-sized workers, and so get a ride home again. It is very 
probable that they take a run out merely for air and exercise. The largest 
class of what are called workers are, I believe, the directors and protectors 
of the others. They are never seen out of the nest, excepting on particular 
occasions, such as the migration of the ants, and when one of the working 
columns or nests is attacked; they then come stalking up, and attack the 
enemy with their strong jaws. Sometimes, when digging into the burrows, 
one of these giants has unperceived climbed up my dress, and the first inti- 
mation of his presence has been the burying of his jaws in my neck, from 
which he would not fail to draw the blood." 

During his study of Atta in the province of Rio Grande -de Sul, Brazil, 
Fritz Miiller appears to have reached independently the same conclusion 
as Belt. A letter directed to Charles Darwin and published in 'Nature' 
during 1874 contains the following remarks: "As to the leaf-cutting ants I 
have always held the same view which is proposed by Mr. Belt, viz. that they 
feed upon the fungus growing on the leaves they carry into their nests, 
though I had not yet examined their stomachs. Now I find that the con- 
tents of the stomach are colorless showing under the microscope some minute 
globules, probably the spores of the fungus. I could find no trace of the 
vegetable tissue which might have been derived from the leaves they gather; 
and this I think, confirms Mr. Belt's hypothesis." 

Although observations on the habits of the Attii continued to be pub- 
lished from time to time the suggestions of Belt and .Miiller were either over- 
looked or ignored for nearly twenty years. In his studies on Atta texana, 
which, like those of Buckley, Lincecum and Townsend, were carried on at 
Austin, Texas, McCook (1879a, 18796, etc.) accurately described the formi- 
caries and fungus gardens. He found the nests to consist of several chambers 
or pockets, sometimes as much as 2 ft. 10 inches long, 12 inches broad and 
8 inches high. The fungus gardens within these chambers are correctly 
described as "masses of a very light, delicate leaf -paper wrought into what 
may be properly called 'combs.' Some of the masses were in a single hemi- 
sphere, filling the central part of the cave, others were arranged in columnar 
masses 2^ inches high, in contact along the floor. Some of these columns 
hung, like rude honeycomb or wasp nests from roots which interlaced the 
chambers. The material was in some cases of a gray tint, in others of a 
leaf -brown. It was all evidently composed of the fibre of leaves which 
had been reduced to this form within the nest, probably the joint action of 
the mandibles and salivary glands. On examination they proved to be 
composed of cells of various sizes, irregular in shape, but maintaining pretty 
constantly the hexagon. Some of the cells were one-half inch in diarneter, 
many one-fourth inch, most of them one-eighth inch, and quite minute. 



Bulletin American Museum of Natural History. [Vol. XXIII, 

Large circular openings ran into the heart of the mass. Some of the cells 
were one inch deep; they usually narrowed into a funnel-like cylinder. 
Ants in great numbers, chiefly of the small castes, were found within these 
cells. In the first large cave opened were also great numbers of larvae. 
The material was so fragile that it crumbled under even delicate handling, 
but a few specimens of parts of the ant's comb, with entire cells, were pre- 
served and exhibited." Although McGook knew of Belt's opinion that 
these masses of triturated leaves serve merely as a culture medium for the 
growth of edible fungi, and even saw the film of h}'ph8e, he nevertheless 
preferred to interpret the latter as "only what might have been expected 
under such environment," and expressed the belief "that the ants feed 
upon the juices of leaves." He fully appreciated the extraordinary exca- 
vating powers of A . texana. "The ability of these emmet masons to excavate 
vast halls and subterranean avenues is remarkable. Several holes in the 
vicinity of Austin were visited, out of which 'beds' or nests of ants had been 
dug by an old man who used to follow the business of ant killing. These 
holes were nearly as large as the cellar for a small house. One such exca- 
vation, about three miles from Austin, was 12 feet in diameter and 15 feet 
deep. At the lowest point had been found the main cavity, quite as large 
as a flour barrel, in which were found many winged insects, males and 
females, and quantities of larvae. This nest was situated 669 feet from a 
tree that stood in the front yard of a house which the ants had stripped." 
McCook examined and reconstructed the tunnel excavated by the ants in 
order to reach this point and found that although its course varied from^ 
18 inches to 6 feet below the surface it deviated little from a direct line and 
gave off a couple of branch tunnels to a peach orchard 120 feet distant; 

In 1880 Morris studied the habits of a small Attiine ant (Trachymyrmex 
septentrionalis) which he had discovered near the village of Tom's River 
on Barnegat Bay, New Jersey. During December of the same year McCook 
communicated this discovery to the Philadelphia Academy of Sciences and 
during the following year (1881) Morris published his own observations in 
the 'American Naturalist.' Both authors regarded the fungus-gardens as 
subterranean "combs" adapted for incubating the brood. Morris saw 
the ants. carry in and incorporate into their fungus gardens the leaves of • 
seedling pines, the flowers of cow wheat (Melampyrum americanum) and 
"the droppings of certain larvae that feed on oak-leaves." The nest is 
described .by both authors and figured by McCook as consisting of two 
spherical chambers, one above the other and connected by a short gallery. 
The entrance was oblique and about 2 inches in length. The upper chamber 
was 1^ inches in diameter, the lower 3 inches. The former was empty, the 
latter contained the "combs" suspended from rootlets that had been left 



1907.] Wheeler; Fungus-growing Ants of North America. 681 

intact while the ants were excavating the chamber. Morris's description of 
these "combs" is more accurate than McCook's. 

Brent in 1886 described the nesting habits, etc., of the large Atta cepha- 
lotes of Trinidad: "A good sized mango tree, at least as large as an average 
apple tree, I saw stripped of every leaf in one night, and greater feats than 
this are recorded of these ' Fourmi Ciseaux,' as they are called by the Creoles." 
Brent gives a diagram of the nest and describes a tunnel leading from the 
lowermost fungus-chamber to a still lower level. He "invariably found 
this lower tunnel wherever the. inclination permitted its construction" and 
has "no doubt that it is constructed as a drain, and that the ants know as 
much about the advantage of thorough drainage as they have been proved 
to know, by many eminent observers, of those of other sanitary matters." 
Some of the chambers of the nest are described as 3 feet in diameter. He 
mentions Amphisbsenians as living in the nest and eating the ants. In 
regard to the use to which the leaves are put, Brent says: "A solution of 
arseniate of soda was next sprinkled upon orange leaves, which were strewn 
upon the mound. These were eventually cleared away, although at an 
immense sacrifice of life. This points, I think, to the true ant food, since 
unless the juices of the leaves as they were sawed up were swallowed, the 
poison would have no effect. This idea is strengthened by the fact that 
fiery and strongly aromatic plants as well as those with poisonous, milky 
juices are carefully avoided. No solid food is found in the crops of the insect 
at any time, but if these are examined after the insects have been engaged in 
leaf-cutting, they are found full of green leaf juice." Later he says : "The. 
larvae are embedded in a soft woolly matter which proved to be the finely 
masticated parenchyma of the leaves. Thus a use was found for the leaves, 
although it reflects seriously upon the supposed sagacity of the ants that 
they should procure so many more than are required for the purpose." 

Emery (1890) appended a brief ethological note to his description of 
Acromyrmex landolti of Caracas, Venezuela. Simon wrote him that "this 
ant makes extensive formicaries with several entrances, each surmounted 
by a column or chimney of straws 10-15 cm. high, in which lives a large 
spider of the genus Ctenus. Simon never saw the ants carry in pieces of 
■leaves like Atta sexdens and believes that they confine themselves to collect- 
ing pieces of dried grasses." 

Observations on A. cephalotes in Trinidad were resumed in 1892 by 
Tanner in two important papers, which, owing to their publication in an 
obscure serial, have been overlooked by subsequent students. He was the 
first to study Attii in artificial nests and to prove that not only the adult ants 
but also the larvte feed on fungus hyphte. In his first paper (1892a) he 
describes the manner in which the workers triturate the leaves: "Each 



682 . Bulletin American Museum of Natural History. [Vol. XXIII, 

forager drops the portion of the leaf in the nest, which is taken up as required 
by the small workers, and carried to a clear space in the nest to be cleaned. 
This is done with their mandibles, and if considered too large it is cut into 
smaller pieces. It is then taken in hand by the large workers, who lick it 
with their tongues. Then comes the most important part, which almost 
always is done by the larger workers, who manipulate it between their man- 
dibles, mostly standing on three legs. The portion of the leaf is turned 
round and round between the mandibles, the ant using her palpi, tongue, 
her three legs and her antennse while doing so. It now becomes a small 
almost black ball, varying in size from a mustard seed to the finest dust shot, 
according to the size of the piece of the leaf that has been manipulated. The 
size of the piece of the leaf is from ^ by ^ of an inch, to | by J of an inch. 
1 do not wish it to be understood that only one class of workers manipulate 
the leaf, for all seeni to take to it very kindly on emergency. Even the 
smallest workers will bring their tiny ball to where the fungus bed is being 
prepared. These balls, really pulp, are built on to an edge of the fimgus bed 
by the larger Avorkers, and are slightly smoothed down as the work proceeds. 
The new surface is then planted by the smaller workers, by slips of the fungus 
brought from the older parts of the nest. Each plant is planted separately 
and they know exactly how far apart the plants should be. It sometimes 
looks as if the plants had been put in too scantily in places, yet in about 40 
hours if the humidity has been properly regulated, it is all evenly covered 
with a mantle as of very fine snow. It is the fungus they eat, and with small 
portions of it the workers feed the larvae." 

In his second paper, published the same year (December, 1892), Tanner 
describes the eggs and larvae of A. cephalotes and the method of feeding the 
latter, together with certain observations which go to show that workers 
lay eggs capable of developing into other workers or even queens. The 
eggs become enveloped in a "pearly white fluffy growth." The larvse which 
hatch from these eggs "are usually placed on the top of the nest and are 
constantly attended by the smallest workers — the nurses — who separate 
them into divisions according to their size. At first it seemed a mystery, 
how these minute grubs could be fed so systematically, knowing that each 
individual larva was only one among so many, yet certain it was, that all 
were equally attended to. Further observations showed that nature had 
provided most efficiently for them to ask for food when they required it. 
This the larvae do by pouting their lips ; at this notification of their require- 
ment the first nurse who happens to be passing stops and feeds them. The 
nurses are continually moving about among them with pieces of fungus in 
their mouths ready for a call for, food. The nurses feed the minute larvae 
by merelj' brushing the fungus . across their lips showing that the spores 



1907.] Wheeler, Fungus-growing Ants of North America. 683 

alone are sufficient for its food at that period of its life. But it is not so 
when the larvae have increased so much in size, that the pout can be seen 
without a glass, for then the whole piece after having been manipulated by 
the nurse's mandibles into a ball, in the same manner as'the" leaves are 
served, when they are first brought into the nest, is placed in its throat and 
if that is not sufficient the pout continues when the next one and even the 
next passing proceeds with the feeding, till the pout is withdrawn, showing 
that it is satisfied. No further notice is then taken of it by the feeders, until 
it agains asks for a meal by pouting later on in the day." 

In 1893 a nephew of the celebrated Fritz Miiller, Alfred Mceller, who 
was given a grant of 5,000 marks by the Berlin Academy of Sciences for 
the purpose of studying the habits of the Attii at Blumenau in the province 
of Rio Grande do Sul, published the most important of existing works on 
these insects and their relations to the fungi which they cultivate. He 
studied several species of Atta belonging to the subgenus Acromyrmex {dis- 
cigera, coronata, octosfinosa, mwlleri) and of the genera Afterostigma {jiilo- 
suTfi, mwlleri, wasmanni, and an undetermined species) and Cyphomyrmex 
{auritus, strigatus). A. octosfinosa and discigera, which nest in the woods, 
form truncated cones of dead leaves and twigs, beneath which they excavate 
a single chamber containing a large fungus garden sometimes IJ meters long. 
A. mwlleri has similar habits, but coronata resembles the species of the sub- 
genus Atta s. str. in forming several chambers, each with its own fungus 
garden. In all of these species the garden is built up on the floor of the 
chamber in the form of a loose sponge-work of triturated leaf-fragments 
permeated with fungus hj'phse which he describes as follows: "Over all 
portions of the surface of the garden are seen round, white corpuscles about 
i mm. in diameter on an average, although some of them are fully i mm. 
and sometimes adjacent corpuscles fuse to form masses 1 mm. across and 
of irregular form. After a little experience one karns, to detect, these cor- 
puscles with the naked eye as pale, white points which are' everywhere abun- 
dant in all the nests. Under the lens they sometimes have a glistening 
appearance like drops of water. They are absent from the youngest, most 
recently established portions of the garden, but elsewhere uniformly distri- 
buted, so that it is impossible to remove with the fingers a particle too small 
to contain some of the white bodies. I call these the 'kohlrabi clusters' 
of the ants' nests. They constitute the principal, if not the only food of 
the species of Atta." These clusters are made up of the "heads of Kohlrabi," 
which are small terminal dilatations of the hyphse of a spherical or oval form. 
Mqeller confirmed Belt's observations on the solicitude of the ants for their 
gardens, and showed that these insects in artificial nests will completely 
rebuild these structures within 12 hours after they have been disintegrated 



684 -Bulletin American Museum of Natural History. [Vol. XXIII, 

or scattered. He also saw the ants eating the fungus and was able to satisfy 
himself that the different species of Atta will eat the Kohlrabi from one 
another's colonies but not that of Apterostigma or Cyphomyrmex. He 
gives the following interesting description of the way in which the leaves 
are comminuted by the workers. "The manipulation of the pieces of 
leaves is the same in all the Atta species and the following description holds 
good uniformly for all of them. The ant first cuts the leaf it has brought 
in through the middle and then busies itself with only one of the halves, 
cutting off another piece, and so on. When the piece of leaf which it has 
retained is sufficiently small so that it can be turned round and round be- 
tween its fore-feet with the aid of its jaws, it is felt of on all sides and turned 
in all directions as if the insect wished to get a clear idea of its form. Then 
an even smaller piece is cut off and this is repeated, till the piece that is 
retained is hardly longer than the ant's head. The rejected pieces are 
picked up by other workers and treated in the same manner. Then the 
ant holds the little piece between it's fore-feet with the sharp edge directed 
towards its mouth and begins to pinch its edges at short intervals around 
the circumference without ever cutting through the substance. The piece 
thus manipulated shows fine, radial ridges under a good lens. The surface 
of the leaf is also abraded with the points of the mandibles, wounded, so to 
speak, so that it soon becomes soft. Then the ant kneads it with the feet 
and again inserts her jaws into the pellet thus formed in order to mould it 
thoroughly. Again and again the jaws close upon the pellet while the feet 
press it and place it in a new position, and again it is kneaded. This ma- 
nipulation is carried on with great care and deliberation, and I have several 
times observed that an ant will spend a quarter of an hour in making such 
a pellet. When it has become a soft mass, the worker takes it in her jaws 
and seeks a suitable spot for it in the portion of the garden that is just being 
built. Once I saw an ant that had found such a spot, actually jab the pellet 
into the garden with a jerk of her head and a simultaneous opening of her 
jaws, and then carefully pat it down with her fore-feet. Another time a 
worker laid her pellet in a breach of a newly erected circular wall, and then 
shook and pushed it into the depression, like a mason setting the last brick 
in a fresh layer of mortar. During all of this work, the antennae are contin- 
ually moving and palpating the pellet just as they are while the ant is feed- 
ing." Into the new material thus added to the garden the fungus hyphse 
grow very rapidly. By afternoon pellets built in during the morning hours 
have become permeated in all directions with mycelium. Belt supposed 
that the smallest workers or minims comminute the leaves and build up 
the fungus gardens.' According to Moeller, however, this is. the office' of 
the mediae, as the leaves are too thick to be manipulated by the smallest 



1907.] Wheeler, Fungus-growing Ants of North America. 685 

workers. The latter have another function, namely that of weeding the 
garden and keeping down the growth of spores belonging to alien fungi. 
Moeller emphasizes the remarkable fact that the gardens are pure cultures 
although the hairy, rough-bodied workers must be continually bringing into 
the nest all sorts of spores and bacteria. It is probable also, that the minims 
are instrumental in producing the "kohlrabi heads" as these are not devel- 
oped when the mycelium is grown in artificial culture media apart from the 
influence of the ants. He summarizes the results of this portion of his- 
studies in the following words: "All the fungus-gardens of the Atta species 
I have investigated, are pervaded with the same kind of mycelium, which 
produces the 'kohlrabi clusters' as long as the ants are cultivating the 
gardens. Under the influence of the ants neither free aerial hyphse nor 
any form of fruit are ever' developed. The mycelium proliferates through 
the garden to the complete exclusion of any alien fungus, and the fungus 
garden of a nest represents in its entirety a pure culture of a single fungus. 
The fungus has two different forms of conidia which arise in the garden 
when it is removed from the influence of the ants. The hyphag have a 
very pronounced tendency to produce swellings or diverticula, which show 
several more or less peculiar and clearly differentiated variations. One of 
these which has presumably reached its present form through the influence 
of cultivation and selection on the part of the ants, is represented by the 
'kohlrabi heads'." 

A number of experiments were undertaken by Moeller for the purpose 
of ascertaining the behavior of the fungus in the absence of the ants. Under 
these conditions he found that the mycelium produces aerial hyphse, the 
"kohlrabi clusters" and "heads" disappear and soon the fungus breaks 
up into masses of bead-like conidia. "As long as the ants are active in their 
garden, there is never either in it or in its immediate vicinity the slightest 
trace of an alien fungus, and, under these circumstances, the mycelium per- 
vading the garden never produces aerial hyphee or conidia." If, however, 
a few of the ants happen to be left in the garden, the development of aerial 
hyphte is retarded, and though Mceller did not observe the process directly, 
he is certain that these hyphse must be bitten off by the ants as soon as they 
make their appearance. "A relatively very small number of workers suf- 
fices to restrain the growth of the aerial hyphse. But if the number is too 
small, the aerial filaments begin to appear sporadically. The ants are 
unable to move about in the dense growth of sprouting filaments and have 
to beat a retreat before the rapidly rising hyphal forest. This, however, as 
soon as it has acquired a little, headway, proliferates mightily, and it is an 
amazing sight to behold the poor insects, tirelessly active till the last mo- 
ment, fleeing before their own food-plant. If some of the larvse and pupae 



686 Bulletin American Museum of Natural History. [Vol. XXIII, 

are still present, they are rescued. The last resort is the vertical wall of the 
glass, up which the insects creep and where they huddle together, while over 
the wide plain of the garden the fungus proceeds to the conidia-producing 
stage." 

Moeller next undertook to determine the systematic position of the fungus. 
He naturally supposed that the discovery of the fruiting form would show it 
to be an asco- or basidiomycete. Although he failed to raise either of these 
forms from his mycelial cultures he succeeded on four occasions in finding 
an undescribed agaricine mushroom with wine-red stem and pileus growing 
on extinct or abandoned Acromyrmex nests. From the basidiospores of this 
plant which he called Rozites gongylophora, he succeeded in raising a myce- 
lium resembling in all respects that of the ant gardens. Three of the species 
of Acromyrmex did not hesitate to eat portions both of this mycelium and 
of the pileus and stem of the Rozites. He believed therefore that he had 
definitively established the specific identity of the fungus cultivated by the 
ants. 

The species of Apterostigma investigated by Moeller usually' nest in 
cavities in rotten wood which is often also inhabited by other insects. The 
fine wood castings and excrement of these insects are used by the ants as 
material with which to construct their fungus-gardens. A. wasmanni con- 
structs the largest nests, and it is only in the gardens of this species that the 
mycelium produces structures analogous to the "kohlrabi heads" and 
"clusters" oi Acromyrmex. The heads, however, are club-shaped instead 
of spherical dilatations of the hyphse. As it produces only irregular swellings 
on the hyphse Moeller believes that Apterostigma represents a much lower 
stage in fungus-culture than the species of Acromyrmex. The Apterostigma 
are, however, very adaptable since they readily collect caterpillar excrement 
or even farina and incorporate these substances into their gardens. Moeller 
states that all the species of this genus cultivate the same fungus, . which 
must be a distinct species as the ants will not eat the fungus grown by Acro- 
myrmex. The gardens of pilo.ium, mwlleri and another undetermined 
Apterostigma, which live in small colonics of only 12 to 20 individuals, are 
suspended from the roofs of the small cavities, 3 to 4 cm. in diameter, in 
the rotten wood and exhibit a peculiar structure not seen in other Attii. 
"The garden is often completely, or at least nearly always in great part, 
enclosed in a white cob-web-like membrane. It'was often possible to obtain 
a view of uninjured nests of A. pilosum that had been excavated in clefts 
of the rotten wood. In such eases the envelope enclosed the whole fungus 
garden like a bag with only a single orifice or entrance. The envelope is 
attached in a pendent position to the surrounding wood, roots or particles 
of earth by means of radiating fibres, and this explains why the gardens 



1907.] Wheeler, Fungus-growing Ants of North America. . 687 

are so easily torn asunder while the nest is being uncovered." Even in 
captivity these ants persisted in hanging their gardens to the sides of the 
glass dishes in which they were kept. "Microscopical examination shows 
that the envelope consists of the same, loop-like hyphfe as the remainder 
of the garden. Such a structure cannot be produced by the fungus except 
under extraneous influences. We must assume that the ants bring about 
the development of the envelope, that they direct or coerce the growth of 
individual hyphas with their antennae or fore legs, spread them out into a 
layer and bite off the recalcitrant hyphse that grow out from the surface." 
Moeller succeeded in cultivating the mycelium of the Apierostigvia gardens 
in artificial media, but he failed to obtain the fruiting stage. He believes, 
however, that the fungus is a basidiomycete. 

The two species of Cypkomyrmex observed by Moeller were found nesting 
under bark or in rotten wood like Apterostigma. The largest gardens 
of C. strigaius are only 8 cm. long, whereas those of C auritus may attain 
a length of 15 cm. and a breadth and height of 5 cm. These gardens are 
never pendent and never enclosed in a mycelial envelope. In other respects 
they resemble those of Apterostigma and are grown on the same substrata. 
The heads are developed as long, irregular swellings in the hyphje and 
therefore represent a more primitive and imperfect stage than those of 
Acromyrmex. Although he was unable to obtain the fruiting stage, Moeller 
nevertheless believed that the fungus of the species of Cypkomyrmex is 
different from that cultivated by the ants of other genera. He concludes 
his paper with a few interesting notes on the breeding habits of the Attii. 
The eggs of Acromyrmex are laid in masses and embedded in loosely woven 
hyphee which enable the ants to carry them about in packets. The pupse, 
too, are often enclosed in hyphse, but this is not the case with the larvae which 
are kept clean and shining. 

In 1894 von Ihering, in an interesting paper on the ants of Rio Grande do 
Sul, records a number of observations on Attii (Atta sexdens, Mosllerius 
striatus, Acromyrmex lundi, niger and Cyphomyrmex morschi). His general 
account of the nests of A. sexdens agrees with that of preceding authors 
who have studied the large Atiw.s. str., and comprises also an interesting 
observation quoted from a former paper (1882) on the importance of these 
insects in reversing the position of . earth strata: "A piece of pasture land 
had been marked off by a recently excavated ditch several feet deep. The 
soil in this place, as generally in the surrounding country, consisted of sand. 
Beneath this in many portions of the region there was a stratum of heavy 
red clay at a depth of four feet or more. What attracted my attention in 
this ditch was the fact that here the clay lay uppermost in a layer about 1 dcm. 
thick. The explanation of this condition was not the result of geological 



688 Bulletin American Mv'seum of Natural History. [Vol. XXIII, 

but of zoological investigation, for closer inspection soon showed that the 
ants are responsible for the inversion of the normal position of the strata. 
It was the work of Atta sexdens. It is very doubtful whether such an 
enormous task can be accomplished by any insects except the large species 
of Atta." Von Ihering observed the marriage flight of A. sexdens and the 
digging of the nests by the recently fertilized females, an instinct mani- 
fested even by individuals whose gasters have been bitten off by birds. 
A. sexdens extends southward in Brazil only to the Cebus-line (latitude 30°), 
The nests of Acromyrmex lundi are excavated to a depth of 50-60 cm. 
and consist of a single chamber with a cubic capacity of J to 1 litre, in older 
nests 5 to 10 times as great. This cavity contains a single fungus garden 
and is connected with the surface by means of a large horizontal or tortuous 
gallery 1-2 m. long. From the nest-entrance, branching, well-worn roads 
lead off over the surface often to a distance of 40 m. and further, and it is 
along these that the ants travel to and from the grasses which they cut down 
together with their green seeds. This ant carries the exhausted portions 
of the fungus garden out of the nest and deposits them on a refuse heap. 
The same is true of Mollerius striatus. This species clears the ground of 
vegetation around its nest entrance which is surmounted by a crater. Like 
A. lundi it collects pieces of grass, flowers, leaves, etc. A. niger nests in 
thickets between the roots, where it excavates its nest at some distance 
from the entrance. It does not confine its cutting operations largely to 
grasses like lundi and striatus but attacks manj^ other plants and is therefore 
of greater economic importance. 

Cyphomyrmex morschi nests in the soil, where it excavates a chamber 
about the size of an orange and containing a fungus garden of leaf detritus 
covered with mycelium. The entrance is surmounted by a circular crater. 

Von Ihering is one of the few who have considered the question of the 
origin of the fungus-raising instincts of the Attii. His remarks on this 
subject will be considered in the concluding portion of this article. 

Urich, in two papers published during the same year (1895a, 18956) 
records a number of observations on several of the Attii of Trinidad {Aita 
sexdens, A. cephalotes, Acromyrmex octospinosus, Trachyynyrmex urichi, 
Sericomyrmex opacus, Apterostigma urichi, A. mayri and Cyphomyrmex 
rimosus). His account of the large species of Atta adds little of interest to 
that of previous authors. On two occasions he found the dealated females 
of Acromyrmex octospinosus "working just as hard and engaged in the same 
occupation as the neuters, viz: cutting leaves and carrying them to the nest. 
They all issued from the same nest and therefore could not have been 
mothers of new colonies." He "also noticed that several females lost their 
wings in the nest without any marital flight, although a few weeks later the 
winged ones swarmed out in the usual way on a damp evening." 



1907.] . Wheeler, Fungus-growing Ants of North America. 689 

The nest of Trachymyrmex urichi is "excayated in clayey soils and 
never anywhere else. It consists of one chamber at about the depth of 
a foot and is never directly under the entrance hole, but always on one 
side at right angles and about 9 inches away from it. It has a habit of carry- 
ing the particles of earth which result from its mining operations a little 
way from the entrance hole, say about a foot, and deposits them in a small 
conical heap .... These ants also cultivate a fungus and if it is not Roziies 
gongylopJiora it is very much like it. . . .Any' roots of plants going through 
the ants' chamber are not cut away, but are made to suspend their mushroom 
gardens which are in their case regular hanging gardens .... They are noc- 
turnal in habits and when disturbed sham death." They "seem to like 
small fallen flowers and the fruit of various kinds of plants to be found in 
gardens, but at the same time they do not despise rose plants, especially 
the young and tender shoots^ They are not at all energetic and are very 
slow in their movements." 

The habits of Apterostigma urichi are described as follows: "Unlike 
Atta this species does not excavate its nests but builds them in rotten trunks 
of trees. . . .They are built in hanging position, i. e., the ants start working 
from the top, but never let the nest touch the bottom of the cavity. Unless 
the garden is quite recent and small it is always enclosed in a delicate white 
covering, which at first sight looks like fine cobweb, with an exit hole at the 
bottom. The nests therefore look like a more or less rounded ball and are 
never larger than an apple. On breaking away this delicate covering a 
small mushroom garden is found consisting of irregular cells in which the 
ants, larvse and pupse are scattered." The fungus is similar to that described 
by Moeller for the Brazilian species of Apterostigma. "The gardens are 
always found under rotten wood and the ants invariably use the excrementa 

of wood-boring insects as a medium for growing their fungus on The 

colonies of these ants are small, not numbering more than 20 or 30 dark 
brown workers, all' of about the same size, viz. 6-6 J mm. and with abnormally 
long legs which measure 7-7J mm. without the hip. They are of nocturnal 
habits." The smaller A. mayri constructs similar gardens in dark cavities, 
not only under rotten wood but also under large stones. It, too, collects 
the excrement of wood-boring insects, but is also fond of fruits or even parts 
of flowers. The mycelium has the kohlrabi aggregated into regular clusters 
and according to Urich represents a more advanced condition than that of 
A. urichi. The ants are nocturnal and sham death for many seconds. 

Urich has also given us the only existing account of the. habits of a 
Sericomyrmex (S. opacus). "The nests of these ants are found commonly 
about Port of Spain, in gardens, in the grass as a rule, but sometimes in the 
flower beds, and from their peculiar raised entrance can be readily recognized. 

[Sept., 1907.1 ■ ■ 43 



690 Bulletin American Museum of Natural History. . \yo\. XXIII, 

They -are always excavated in clayey soil, and the raised entrances, which 
are more or less cylindrical, are constructed with the particles of earth result- 
ing from their mining operations and are about an inch in height. In young 
colonies this entrance leads into a small chamber, about six inches below 
the surface of the ground, situated not at the end of the gallery but either 
to the left or right of it. ^_s the colony increases the ants do not enlarge this 
original chamber, but, piercing its side, form another chamber near it with 
a small entrance hole. In large colonies, which never consist of more than 
about 200 individuals, a nest consists of two or three chambers which open 
on the original excavation. This is no longer used for growing the fungus 
■ in, but forms a sort of ante-chamber which generally contains material 
brought in by the ants to grow their mushrooms on, which is deposited here 
and gradually made use of. The chambers adjoining are more or less round, 
with a diameter of about 2t-3 inches, and any. 'small roots of plants growing 
through them are not cut away but used by the ants to hang their mushroom 
gardens on. These fill the interior of the chamber and consist of a gray 
spongy mass consisting of a great number of little irregular cells and resem- 
bling a coarse sponge, amongst which are scattered larvae, pupse.and ants. 
The walls of the cells consist of small round pellets resembling dust shot and 
are penetrated by and enveloped in white fungus hypha;, which hold the 
mass together. Strewn thickly upon the surface of the garden are to be 
seen round white bodies about a quarter of a millimeter in diameter. These 
are what Moeller terms "Kohlrabi" clumps, and consist of an aggregation 
of hyphse with special swellings at their ends. It is on this that the ants 
feed. The fungus found by Mcellei in the nests of the Brazilian fungus 
growers (Acromyrmex) is the Rozites goiigylophora, Moeller, and if it is not 
the same species cultivated by S. opacus it is, at any rate, very nearly related 
to it. As material' to grow their mushrooms on the ants make use of particles 
of fruit, flowers, and leaves, but prefer fruit. They do well in artificial 
nests, constructed on Sir John Lubbock's plan, and are easy to watch. I 
have tried them with all kinds of vegetable products; they have taken orange, 
banana, rose petals and leaves and once they even made use of the dried 
glue from the back of an old book lying near their nest, but that day they 
had nothing else ; if the choice be left to them they invariably take fruit and 
seem to prefer the orange amongst these. Very small particles of the white 
skin of the oranges are torn off, and after undergoing a slight kneading 
process in the ants' mandibles, are planted in the nest. The neuters are 
all of the same size, varying but slightly and never exceed 4 mm. in length. 
They are more diurnal, in their habits than other species of fungus growers, — 
but also work a little at night. I have found winged forms in the nests in 
the month of July." 



1907.] Wheeler, Fungus-growing Ants of North America. 691 

Urich is responsible for the erroneous statement that Cyphomyrmex 
rimosus "does not cultivate any fungus," a statement which has been re- 
peated by subsequent writers (Forel, Emery). 

In 1896 Swingle read a paper on Trachymyrmex se-ptentrionalis ( = tardi- 
grada auct.) before tlie American Association for the Advancement of 
Science. He says: "In July of this year I exainined some colonies of Atta 
tardigrada, which Mr. Pergande had found in the vicinity of Washington. 
The nests are small subterranean cavities, 6-10 cm. in diameter, situated 
from 2 to 15 or 20 cm. below the surface. Some nests have one cavity, 
others two. Almost the whole cavity is filled with a grayish material loosely 
and irregularly connected together. By watching the ants, it was deter- 
mined that they carried into their nests the excrements of some leaf-eating 
insect, lying on the ground under neighboring oak-trees. The same material 
was found to constitute at least a large part of the substance filling the nest. 
Even with a low magnifying lens, tufts of minute sparkling bodies could be 
seen on the fragments of the fungus garden, while the whole mass was 
interpenetrated by the white mycelium of a fungus. Examination with 
higher magnification showed that the glistening tufts were really composed 
of 'Kohlrabi' even more perfectly spherical than figured by M. Moeller. 
The mature 'Kohlrabi' were very much larger than the mycelium below, 
being 22 to 52 fi wide, and 30 to 56 // long, while the supporting mycelial 
threads were only 4 to 8 ,« in diameter. There are no septa dividing the 
' Kohlrabis ' from the mycelial threads. The whole appearance of the fungus 
is strikingly similar to that found by Moeller, and it is by no means impossible 
that it will prove to be the same species though the Kohlrabis are nearly 
twice as large as what he reports." 

Forel (1896a-c, 1897, 1899-19006) has recorded a number of obser- 
vations on the Attii of Colombia (^1. sexdens, cephalotes and Iwvigata; 
Acromyrmex octospinosus, and species of Trachymyrmex, Sericomyrmex, 
Mycocepurus, and Apterostigma) . He excavated one of the huge nests of 
A. sexdens belonging to an extensive colony at Rio Frio (18966). "This 
nest looked like an immature volcano and consisted of a mass of 12 to 20 
fused craters. The whole nest was 5 or 6 m. in diameter and about 1 m. 
high. The largest (median) crater was about 60 cm. in diameter, 28 cm. 
high, and had an opening below of about 3J cm. The smaller accessory 
. nests in the neighborhood (100 to 200 steps distant) had only 2-3 craters and 
were much smaller. There are two kinds of craters; one consisting of sand 
or soil of a gray color and consisting of the excavated earth, the others are 
brown and consist of the rejected and useless remains of the gardens, i. e., 
the portions that have been exhausted by the fungi, thrown out in this 
manner in the form of brown pellets. The medium-sized workers are 



692 Bulletin American Museum of Natural History. [Vol. XXIII, 

seen continually coming out of the latter craters laden with brown pellets 
which they cast aside, while into the gray craters a stream of the same kind 
of workers is entering in an almost continuous procession laden with green 
leaves. Some small workers also stand around the openings. On disturb- 
ing the nest one is severely attacked by the largest workers. With their 
sharp jaws, worked by enormous muscles, they can bite so severely as to 
bring the blood; in fact, a small artery in my little finger was severed by 
one of these workers. The wounds were as much as 4 mm. in length. 
Nevertheless Mr. Bradbury, a native and myself attacked the nest with a 
shovel and dug into it deeply. Thousands of the large workers rushed out 
at us. The half-naked! Indian ran away and I had to retreat from time 
to time with bleeding hands. But the interior of the nest was laid bare. 
This consisted of a number of great cavities, 15 to 20 cm. long and 8-12 cm. 
high and each was nearly always filled with a fungus garden, which looks 
very much like the single garden of the Acromyrmex species. In the laby- 
rinth of this gray to brown garden live thousands of the smallest and medium 
sized workers, together with the whole ant brood. Colossal female larvae 
are there found covered with a regular envelope of larvse of all sizes, so that 
they have the appearance of hedge hogs. The workers held fast to the 
larvse so tenaciousl}^ that I could take them in my hands and even kill them 
in alcohol without their losing their hold. .. .The- large species of Atta 
therefore have not only one but hundreds of fungus gardens. The fungus 
chambers communicate with one another by means of broad galleries 2-3 
cm. in diameter. The lower portion of the garden is uniformly light rust- 
red with white fungus patches, whereas the upper portions are more gray. 
The dark brown portions seem to represent the residuum. The fungus 
garden is so friable that it is impossible to remove it without destroying its 
form. How the old m}'th, or nonsense, that these Atta species line their 
nests with leaves could have originated and could even be revamped by 
McCook is incomprehensible to me . '. . . All the pupse are naked, that is, 
not enclosed in cocoons. The workers have the habit of caiTying their 
straying sisters exactly like our species of Formica (the carried ant is rolled 
under the head of the carrier)." In another place (1899, 19006) Forel says 
that Acromyrmex octospinosus carries its sister workers in the reverse posi- 
tion, i. e., like Myrmica. He also describes (18966) very briefly the nests 
and distribution of A. cephalotes and laevigata. The latter also has very 
large but deeply subterranean nests. It lives more in the mountains at and . 
above an altitude of 1,000 m. and so far do^Ti in the ground that Forel could 
not reach the fungus gardens. Cephalotes is intermediate; its nests are 
nearly as large as those of sexdens and the fungus-gardens have a very 
similar structure and arrangement. The colonies of cephalotes and espe- 



1907.] Wheeler, Fungus-growing Ants of North America. 693 

cially of Iwvigata, are less populous than those of sexdens. The nests of 
cephalotes occur from sea-level to an altitude of more than 1,000 m., those 
of sexdens only in the low-lying regions. 

According to von Ihering (1898) the nest of the Brazilian Atta sexdens 
differs from that of the Colombian form described by Forel. It consists of 
from one to two dozen chambers, each 25-30 cm. in diameter and 12 to 
15 cm. high, with a flat floor and arched ceiling. Each of these chambers, 
fanellas (pots) or pratos (plates) as they are called by the Brazilians, has 
one or more, rarely two, galleries entering it at the side and connecting it 
with the other cavities and the vertical shafts leading to the surface of the 
nest. The chambers are |^ to 1 m. apart and are excavated at a depth of 
4 to 6 m. below the surface or even lower. The fungus gardens are built 
up on the flat floors of the chambers.. Von Ihering found that when the 
nests are inundated the ants at once remove portions of their fungus gardens 
to higher ground. When this is impracticable or the inundation is very 
great, the population of the nest forms a ball held together by the closed 
jaws of the workers and enclosing in its interior a portion of the fungus 
garden and probably also the queen. This ball then floats on the water 
. till carried ashore, when the ants land and start a new nest out of reach of 
the flood. Von Ihering says that his neighbor took advantage of this habit, 
which by the way is also exhibited by several other tropical ants {Anomma, 
Solenofsis geminata, etc.), to free his premises from the leaf-cutting Atice, 
by rowing about in his canoe, catching up the floating balls and throwing 
them into a bucket of boiling water. Von Ihering also gives an interesting 
account of the ifa.?, or virgin queens of Atta sexdens. At the time of swarm- 
ing these are captured in great numbers by the Brazilians. The i9a hunter 
stations himself at the entrance of the nest with his feet in a tub of water in 
order to protect himself from the savage soldiers and workers, and collects 
the females while they are issuing from the galleries. A successful catch 
may yield as many as 12 to 20 litres. The gasters of these ipas, removed 
from the thoraces, legs and heads and roasted with salt, garlic and mandioca 
meal are eaten as a delicacy (' passoca") in many parts of Brazil. 

Forel (1899-1900a, 1901) has also recorded a few notes on the fungus- 
gardens of a colony of Trachymyrmex septentrionalis which he observed at 
Black Mountain, North Carolina, but he adds little to the above cited 
descriptions of Morris, McCook and Swingle. Forel (1905) later pub- 
lished some notes of Gceldi on the nests of Acromyrmex octospinosus, the 
fungus gardens of which are built over the stems of plants and fully exposed 
to the air in the damp forests of Para. Two photographs accompanying 
the article show that this fungus garden consists of a number of separate 
portions unlike the single garden which Urich and Forel describe this ant . 
as making when nesting in the ground. 



694 Bulletin American Museum of Natural History. [Vol. XXIII, 

In 1900 Moreno published some observations on the Mexican Atta 
(probably fervens) but these add nothing of value to what was previously 
known. 

In 1901 I recorded a few notes on Atta fervens and Gyphomyrmex rimo- 
sus dentatus which I observed in Mexico. I was able to convince myself 
that the statements of Urich, Forel and Emery to the effect that the latter 
species makes no fungus-garden, .are erroneous. This ant constructs a 
fungus garden with caterpillar excrement and ciiltivates a peculiar, fungus 
consisting of small yellow nodules, which have been overlooked by previous 
investigators. More recently (1905a) I have found that other va]-ieties and 
subspecies of C. riviosus in Texas, Florida, the Bahamas, Porto Rico and 
Culebra have the same habit. In this same paper I also described briefly 
the habits of Trachymyrmex jamaicensis, and in a subsequent paper (1905ti) 
also those of T. septentrionalis. A fuller account of these various species 
will be found in the third part of the present article. 

M. T. Cook (1906) has very recently studied the habits of Atta insularis 
and has published a few notes on the ravages of this ant in the plantations 
of Cuba. 

The preceding paragraphs deal almost exclusively with observations 
on adult colonies of the Attii and the constitution and care of their fungus 
gardens. ' As soon as these habits had been demonstrated, the question 
naturally arose as to how the ants first come into possession of the fungi 
which they cultivate with such marvellous skill and assiduity. The labors 
of the South American naturalists Sampaio, von Ihering, Goeldi and Jakob 
Huber have supplied the answer to this interesting question. 

Sampaio (1894) on digging up an Atta female ten days after the nuptial 
flight, found her in a cavity with two small Avhite masses, one consisting 
of 50-60 eggs, the other of a filamentous substance which was the young 
fungus garden, though not recognized as such. Three and one half months 
after the nuptial flight he excavated another nest which had an opening to 
the surface of the soil. He found Jiumerous Avorkers of three different sizes 
but all smaller than the corresponding castes in adult colonies. They were 
already cutting leaves and had a fungus garden about 30 cubic centimeters 
in volume. He estimated the number of workers at 150 to 170, that of the 
larvffi and pupfe at about 150 and the eggs at 50. 

The much more important observations of von Ihering (1898), including 
his brilliant discovery of the method of transfer of the fungus culture from 
the maternal to the daughter colony, deserve fuller consideration. Accord- 
ing to this observer there are repeated nuptial flights of the Brazilian Atta 
sexdens from the end of October to the middle of December. These flights 
are essentially like those of other ants. On descending to the earth the 



1907.] Wheeler, Fungus-growing Ants of North America. 695 

fertilized female "rids herself of her easily detached wings by quick motions 
of her legs and then begins to dig her burrow in some spot more or less free 
from vegetation. This canal is nearly or quite vertical and measures about 
12-15 mm. in diameter. It is so narrow that the 'I^a' cannot turn around 
in it, but is compelled to walk backwards whenever she returns to the surface. 
She bites off lumps of earth with her powerful jaws, makes them into a 
pellet by means of loose threads of saliva, brings them up and deposits them 
a short distance from the entrance to the burrow. The earth thus brought 
up forms a circular wall, thickened in front and interrupted behind, about 
4-5 cm. broad in front and at that point 3 cm. from the entrance. The 
burrow varies from 20-30 cm. in length according to circumstances and 
ends in a small laterally placed chamber about 6 cm. long and somewhat 
less in height. As soon as the chamber is completed, the ant closes the upper 
portion of the burrow to a distance of 8-10 cm. from the entrance with 
pellets of earth and this closure becomes more and more compact in the 
course of weeks, probably through the action of the rain. If the nest be 
opened in one or two days, the female will be found in the empty chamber 
unchanged, only more, lethargic, as if exhausted. A few days later one finds 
near the ant a little packet of 20-30 eggs undergoing segmentation. Beside 
them lies a flat heap of loose white substance," only 1—2 mm. in diameter. 
This is the earliest rudiment of the fungus garden. Microscopical examina- 
tion shows that it consists of compact masses of the well-known fungus- 
hyphee, but without traces of "kohlrabi" corpuscles. As time goes on the 
fungus garden grows rapidly and becomes more voluminous till it reaches a 
diameter of about 20 cm. It seems to consist of closely aggregated spherules 
about 1 mm. in diameter. As soon as it has attained this size the transparent 
pyriform globules bud out, which Moeller called 'kohlrabi' and the ant is 
seen to eat them frequently. She always keeps close to the fungus garden 
and in it embeds her eggs. The larger of these soon become larvse. The 
eggs are not spun over with fungus hyphse but have the chorion smooth and 
shining. Eggs are also found in the interior of the fungus mass, which the 
ant keeps rearranging and redistributing from time to time. It was easy, 
for purposes of observation, to transfer the ant to a. terrarium. Without 
excavating anew she remained with her garden on the fresh layer of earth. 
The garden did not grow, but rather diminished in volume, for it is difficult 
to imitate the conditions, especially the precise degree of moisture, in, which 
it grows and develops in its cavity. I failed therefore to keep the ant and 
her garden till the first workers appeared. The time required to accomplish 
this must be between two and three months. Presumably the last phase 
of this first brood period is very precarious, since leaves must be brought 
in to serve as a substratum for the further growth of the fungus garden. 



696 



Bulletin American Mu.-iciim of Ndtiiral Hixtory. [Vol. XXIII, 



In any event, tlie (lc\\'l()j)nu'nt of the ijanlcn is in need of further elucida- 
tion. Aeconlini; to my investio;ation.s, wliich need fuller confirmation, 
the organic substratum is jirovided in the form of malaxated eggs, hut per- 
haps the soil, which is rich in vegct;d)lc ninuld, may itself contain nutrient 
substances .... As soon as the first workers appear, the colony may be 
regarded as established and the o]H'ning u]) of the burrow, the enlarging of 
the first chamber, carrying in of leaves, etc., lead to the well-known condi- 
tions of the adult colony. . .'The preceding description is hardly complete 
without an answer to the (|uestion: Whence come tiic fungus germs for the 
establishment of the new garden?" After .searching the queen for fungus 
.spores concealed about her per.son, von Ihering made the important dis- 
covery that "every Alia queen, on leaving the ])arental nest, carries in the 
posterior portion of lier oral chaml)er a loo.se pellet, .0 mm. in diameter, 
consi.sting of hyphic of Hozitc.i f/anr/i/lophorn, small fragments of bleached 
i. €., chlorophylle.ss leaves, and chitinous bri.stlcs. The last are undoubtedly 
derived from the larvw undergoing ecdysis in the parental nest." Von 
Ihering is of the opinion that the female keeps the pellet of hyphre, etc., 
in her mouth till she has excavated her chamber and then s])its it out where 
it will serve to kindle the fungus garden of the new colony. 

The ob.servations of (Jo'ldi, (Forel lOOo, Ga'ldi 1905 a and h) are little 
more than a confirmation of tho.se of von Ihering. lie maintains that the 
fungus is actually gnjwn on some of the malaxated eggs of the Atta queen, 
who would thus be sacrificing a part of her offspring as a culture medium 

for the fungus that goes to nourish both 
her.self and her workers in their larval and 
adult .stages. 

None of these investigators succeeded 
in rearing an Atla colony from its very 
inception till the hatching of the firstling 
workers and the l)ringing in of the leaves 
for the purpose of keeping up the fungus 
culture. This has been accomplished very 
recently by .lakob Iluber (1905) who be- 
sides c'orrecting a few errors in the work 
of his predcces.sors, has added a number 
of new and important observations. His 
paper, from which the following abstract 
is taken, also contains .several interesting figures from photographs of the 
Atta female, her progeny, and fungus garden. The female expels the pellet 
from her buccal pocket (Fig. 1, v) the day following the nuptial flight. It is 
a little mass .5 mm. in diameter, white, yellowish or even black in color, and 




Fifi. 1. Head of recently fertilizecl 
queen of Aiia scxdens longitiuiinally hi- 
sected. 

a. Mandilde; h, lalihini retracted: 
c, Ijuccal nocket coiitainiiif; ^/, Ilie pelh-i 
of fungus nypliie carried from tlie paren- 



tal nest: c, a'sopliagus 
(After J. Huber.) 



/, oral orilici 



1907.] 



Wheeler, Fungus-growing Ants of North America. 



697 




!■]^^^'s uiul riiiiK'is gar- 
(Ifll in cc!! ol qiiccii Alia ■•^cxdens, 
torty-t'if^lit hours iiftiT tilt' nupliui 
flifc'lit. (After J. Huber.) 



consists of fiinfjus hypliffi iiubeddcil in tlii' siiKstniiccs collected from the ant's 
body by means of tlie striffils on her fore feet <ind thence deposited in her 
mouth. By the third day 6 to 10 cfij^s are laid (Fig. 2). At this time also 
the pellet begins to send out hyphfle in all directions. The female separates 
the pellet into two masses on this or the following day (Fig. 3). For the 
next 10 to 12 days she lays about 10 eggs daily, while I he finigns floeculi 
grow larger and more numerous. At first the eggs and lloccnli arc kept 
separate, but they are soon brought together 
and at least a part of the eggs are |)laced on 
or among the floeculi. Eight or ten days later 
the floeculi have Ijecome so numerous that they 
form when brought together a roimd or ellip- 
tical disc about 1 cm. in diameter. This disc- 
is converted into a disli-like mass with central 
depression in which the eggs and larv.e are 
thenceforth kept. The first larvne api)CMr 
about 14 to IG days after the Affa female has 

completed her burrow, and the first pupa> appear ;d)out a month after the 
inception of the colony. By this time the fimgus garden h;is a diameter of 
about 2 cm. There are no "kohlrabi" corpuscles in the earlier stages, and 
when first seen they arc at the periphery of the disc. .\ wi'ck later the pupse 
begin to turn brown and in a few days the first workers hatch. Hence the 
time ref[uired for the establishment of a colony under the most favorable 
conditions is about 40 days. After this rapid survey of the matter, Iluber 

asks the important (|uestion: How does the 
Attn female mantigc to kccj) the fimgus alive? 
Obviously the small amount of substance in 
the original pellet must soon be exhausted and 
the growing liy])ha; must be supplied with 
nutriment from some other source. His inter- 
esting answer to this ([uestion may be given in 
his own words: ".\fter ciirefully watching the 
ant for hours she will l)e seen suddenly to tear 
a little piece of the fungus from the garden 
with her mandibles and hold it again.st the tip of her ga.ster, which is 
bent forward fortius purpo.se (Fig. 4). At the same time she emits from 
her vent a clear yellowish (jr brownish droplet which is at once absorbed by 
the tuft of hyphiie. Hereupon the tuft is again in.scrted, amid much feeling 
about with the antennte, in the garden, but usually not in the same .spot 
from which it was taken, and is then patted in place by means of the fore 
feet (Fig. 5). The fungus then sucks up the drop more or less quickly. 




Fig. 3. EgRs and fungus gar- 
den in cell of queen Attn sei'dens 
seventy-two hour.s after the nup- 
tial flight. (After J. Huber.) 



698 



HiilUtiii Anicririiii ^[llx(ln)l n] Natural History. [VoL XXIII, 




Fin. 4. Silho\iett(> of ;i ■i""'" -I"' 
sejcda}i< in the act of imimirint: ln-i- fun 
gus Kaficn. (From ati iii>I;iiil iiiu-oii: 
pliotograiili uflci- ,1. Hu!m-i-. ) 



Often sev('i';il of llicsc (li-()|is may l)c clcaiiy seen scattered over the young 
fungus garden [l''ig. <i]. Aceoi-diiio- Id my ohservations this performance 
is repeated nsuaily (ince or tuirc an hour, and sometimes, indeed, even 
more fre(|uently. It can almost always lie observed a number of times in 
siiccessiori when a mother ant that has no fungus, as sometimes happens 

ill the cultures, is given a piece of fun- 
gus belonging to another Attn female or 
111 III! a n (jlder colony. The mother ant is 
visibly excited while she explores the gift 
wiih lier antenui?, and usually in a few 
minutes liegins to divide it up and re- 
build it. At such times she first applies 
each |)i('cc to her vent in the manner 
above described and drenches it with a 
t'ecal droplet." From these observations 
Iluber concludes that the droplet must 
be lif|uid excrement and that the fungus 
owes its growlh lo ihis meilidd df manuring. A direct use of malaxated 
eggs for this ))ur])o,se was never ob.served and could not be detected by mi- 
croscopical examination, although a number of ob.scrvations show that the 
same result may be accomplished indirectly, namely by the female eating her 
own eggs. This habit is so common and ai)|)arently so normal that Huber 
estimates thai 9 out of <'very 10 eggs are 
devoured by I he mollicr, olteii as soon 
as they ai'c laid. The life of the Af/(i 
female in her lilllc cell during all ihis 
time is very rhyllimical. .\l regular in- 
tervals she conscientiously examines the 
walls of the cavity, flattens out the earth, 
etc. .She devoles more time to licking 
and nninuring the fungus garden and, of 
course, lavishes most care on the brood. 
As soon as the larva' appear they are 
fed directly with eggs thrust into their 
nioiilhs by their mother. Huber con- 
cludes ihal Ihis is (heir normal <liel till llie firsi workers liatch. He never 
saw the female either eating the fungus mycelium herself or feeding it to 
the young. .As proof of his conleiilion he ciles the ca.se of one of his Affa 
(|nceiis who brouglil \\\t a brood without ;i fungus garden. With the 
a|)pe;irance of the firslling workers, which ;irc minims, that is members of 
the smallest worker cti.ste, a change comes over the colonv. Thev begin to 




I'i^'. 5. SillHHH'Itt' of a qiu'f'u Atta 
xfj-dciis iciilacing ill tlie fiingit.s garden 
tiifi of mycelium saturated with fecal 
li(]ui<i. {From an in.stantaneoiis i>ho- 
loL-raph after .1. Huber.) 



1907.] 



Wheeler. Fungus-growing Ayits o! North Ameriea. 



G99 



USUI-]) the functions of the mother ant. Tliev inaniii'e the garden, whicli at 
the time of their a|:)pearanee measures iiardly more than 2. .5 em. in diameter, 
and feed the larvw with tlieir mothers' eggs. The workers themselves, 
hov>-ever, feed on the "kohh-ahi" which has been developing on the hypha- 
in the meantime. After about a week some of the workers begin to dig in 
the earth, and ten days after the apjiearanee of the first worker and .seven 
weeks after the inception of the colony, they break through to tlie surface 
of the soil and surrountl the entrance of the nest with a tiny crater of earthen 
pellets. They now begin to ijring in pieces of leaves, knead them up into 
minute v.ad^. and ins.>rt th.'in in the fungus gard 'U. Tiie method of man- 




Fig 6. Fungus garden of Attn sexdens fourteen days after the nujitial fliglit. There are 
about too eggs which the queen has placed in a depression in the middle of the garden. Near 
the periphery there are three drops of the fecal liquid with which the cjueeu manures her garden. 
(After J, Hiiber.) 



uring the garden with fecal droplets seems now to l)e aljandoned. The 
mother Affa henceforth pays no attention to the development of tiie garden or 
to the Isrood, but degenerates into a sluggish egg-laying machine, while the 
multifarious labors of the colony devolve on the workers. In the meantime 
the "kohlrabi" has become .s(j abundant that it can be fed to the larvte. In 
concluding his paper Huber makes the imjjortant observation that fertile 
females of Affa .<<i:vden.^ are readily ado]ited by .strange workers of their own 
species. Such adoptions may be fre(|neiitly resorted to in a state of nature 
and would perhaps account for the enormous size and great age of some of 
the formicaries of the larger s])ecies of Atta, which in this respect resemble 
the colonies of Formira rtijn and F . rx-wrtoidcn in the north temperate zone. 



700 Bulletin American Museum of Natural History. [Vol. XXIII, 

Part II. Descriptions of North American Attii. 

1. Atta texana Buckley. 

Myrmica {Atta) texana Buckley, Proc. Acad. Nat. Sci. Phila., 1860, p. 233, § ^ S". 
Myrmica texana Buckley, Proc. Acad. Nat. Sci. Phila., 1861, pp. 9-10. 
(Ecodoma texana Linoecuji, Proc. Acad. Nat. Sci. Phila., 1867, pp. 24-31. 
(Ecodoma texana Buckley, Proc. Ent. Soc. Phila., VI, 1867, p. 347, no, 62,- g 9 c? . 
Atta fervens Townsend, Amer. Entom. and Botan., II, 1870, pp. 324-325, figs. 202 

and 203, 5 9- 
Atta fervens McCook, Ann. Mag. Nat. Hist., (5) III, 1879, pp. 442-449. ■ 
Atta fervens McCooK, ■ Nature, XX, 1879, p, 583. 
Atta fervens McCook, Proc. Acad. Nat. Sci. Phila., 1879, pp. 33-40. 
(Ecodoma texana Nehrling, Zool. Garten, XXV, 1884, p. 265. 
Atta fervens Dalla Torre, Catalog. Hymen., VII, 1893, pp. 152, 153 (in part). 
Atta fervens Emery, Zool. Jahrb., Abth. f. Syst., VIII, 1894, p. 329. 
Atta fervens Forbl, Biol. Centr. Amer., Hymen., Ill, 1899-1900, p. 33 (in part). 
Atta fervens AVheeler, Amer. Natur., XXXV, 1900, pp. 851-862, 2 figs. ■ 
Atta fervens AVheeler, Trans. Texas.Acad. Sci., IV, no. 2, 1902, p. 13.' ' 

Soldier. (Fig. 7 and PI. XLIX, Fig. 11.) . Length 10-12 mm. . 

Head cordate: without the mandibles broader than long, with rounded posterior 
corners and shallow obtuse occipital excision. Mandibles long, flattened, with a 
large acute apical and 9 or 10 blunt, subequal basal teeth. Clypeus short and broad, 
with bidentate and arcuately excised anterior border. Frontal carinie continued 
as distinct, diverging ridges as far back as the middle of, the head; , their lobes with 
a prominent tooth above the insertion of each antennal scape. Frontal area large, 
triangular, indistinct. Antennse slender. . Eyes convex, hemispherical,' about J the 
distance from ' the anterior to the posterior comers of the head. . Ocelli absent. 
There is a tooth on the lateral carina between the eye and the clypeus, two small 
spines or teeth on the ventrolateral surface of the head, one or two similar, teeth on 
each occipital lobe and behind them a large prominent spine. Thorax with four 
pairs of spines: one small acute pair on the inferior corners of the pronotum, a 
large robust, acute and erect pair, sometimes reduced to conical projections, above 
on the sides of the pronotum; a much shorter, often more slender and less tapering 
pair on the mesonotum, and a long, acute, backwardly directed pair on the epinotum. 
The last are prolonged forward at their bases in the form of a pair of anteriorly con- 
verging ridges. Petiole about IJ times as long as broad, pentagonal from above, 
broadest in the middle; node concave in the middle with a ridge on each side. Post- 
petiole nearly twice as broad as the petiole, about as broad as long," narrowed in 
front, flattened above, with a pair of more pronounced and uneven mesial and a pair 
of shorter and feebler lateral ridges. Gaster oval, broadest at the middle, with 
somewhat angular anterior comers and abruptly conical tip. Legs very long and 
slender'. ' 

Mandibles and clyjreus shining; the former coarsely striatopunctate, the latter 
finely and unevenly punctate. Remainder of body opaque, very finely punctate or 
granular. 

Hairs long, erect or reclinate, curved, golden yellow or fulvous, covering the 



1907.] Wheeler, Fungus-growing Ants of North America. 701 

body and appendages. Pubescence abundant on the body and rather long, of the 
same color as the hairs; absent on the appendages, with the exception of the antennal 
funiculi. 

Ferruginous brown; borders of mandibles black. 

Media. (Fig. 7 and PL XLIX, Fig. 13). Length: 3-9 mm. 

Resembling the soldier but with proportionally smaller head and all the cephalic 
and thoracic spines longer and more acute, especially the posterior occipital and the 
superior pronotal pairs. The latter are often much longer than the epinotal spines 
and curved forward at their tips. 

Minima. (Fig. 7 and PL XLIX, Fig. 14.) Length: 1.5-2.5 mm. 

Head proportionally smaller than in the soldier and media; mandibular teeth 
more acute; lobes of frontal carinas, lateral carins and ventro-lateral surfaces of 
head without teeth. Anterior and posterior occipital spines much reduced. On the 
thorax the superior are not longer than the inferior pronotal spines and much shorter 
than those on the epinotum. Pubescence and hairs miich sparser and more incon- 
spicuous than in the soldier and media. 

Female. (Fig. 7.) Length: 17-18 mm. 

Head without the mandibles, much broader than long, arcuately excised behind, 
with rather straight, anteriorly converging sides. Mandibles and clypeus similar 
to those of the soldier, but the former with at least 12 basal teeth, the latter with the 
two teeth of its anterior border blunter and more prominent. Frontal and lateral 
carinfe with prominent teeth. Spines of anterior occipital and ventro-lateral, surface 
of head reduced to low projections. Posterior occipital spines small but acute. 
Thorax robust, distinctly longer than the first gastric segment; twice as broad as 
the head. Inferior pronotal spines small and acute; superior pair lacking. Scutel- 
lum rounded, convex, without a median longitudinal impression. Epinotum with 
a pair of small, acute, backwardly directed spines, each of which has a prominent, 
elongate swelling in front of its base. Petiole more than twice as broad as long; 
broadest in the middle and produced on each side into a long, slender spine or proc- 
ess. Postpetiole less than twice as broad as the petiole and fully twice as broad 
as long, widest behind with two pairs of truncated lateral projections, of which the 
posterior is the longer. Lower surface with a prominent transverse ridge. Gaster 
nearly as broad as long, but little broader in the middle than at its straight anterior 
border. Anterior corners of first segment rectangular. Legs slender and weak. 

Mandibles, anterior border of clypeus, scapes and legs shining; clypeus and 
mandibles punctate, the latter also very coarsely striated. Remainder of body 
opaque, granular-rugulose. Mesopleurae coarsely rugose. 

Hairs and pubescence tawny, the former dense and erect on the body and ap- 
pendages, the latter sparse, somewhat reclinate and hooked, most conspicuous on 
the head and gaster. 

Deep maroon brown, legs more reddish; borders of mandibles black. Wings 
with ferruginous brown veins and a strong suffusion of the same color in the mem- 
branes, especially along their anterior borders. ^k 

Male. (Fig. 7, and PL XLIX, Fig. 24.) Length: 13-14 mm. 
Head small, without the mandibles but little broader than long, flattened behind 
but not excised, with large and very prominent eyes and ocelli. Mandibles well- 



702 Bulletin American Museum of Natural History. [Vol. XXIII, 

developed, with pointed tips and about a dozen, blunt basal teeth. Anterior border 
of clypeus with two broad blunt teeth and a median excision. Space between frontal 
and lateral carinse concave, elliptical. AntennsB slender. Cephalic spines obsolete, 
except those of the posterior occipital region, which are short, acute and sometimes 
bent downwards at their tips. Thorax through the wing insertions more than twice 
as broad as the head. Mesonotum as broad as long, projecting in front over the small 
pronotum, which has a short, broad tooth at its inferior corner on each side. Scutel- 
lum convex, with a faint longitudinal impression in the middle. Epinotum unarmed. 
Petiole arid postpetiole similar to those of the female, but each side of the former 
sometimes with two spines of unequal length, and the postpetiole is less angular on 
the sides. Gaster as broad as long, elliptical, convex above and below. Hypopy- 
gium broader than long, fenestrate, with its free edge faintly bidentate and not ex- 
cised but instead slightly produced in the middle. Outer genital appendages slender, 
strap-shaped with subparallel borders and obliquely truncated tips. Median pair 
long with infolded edges and geniculate towards the apex, which is flattened and 
provided with a strong basal and two feebler terminal teeth. Wings 22 mm. long. 

Mandibles somewhat shining, finely striate and coarsely punctate. Head and 
thorax opaque, pedicel and gaster slightly shining, Clypeus, frontal area and facial 
concavities uniformly granular, remainder of head coarsely reticulate-rugose. Thorax 
' rather coarsely granular and punctate. Mesonotum with undulating transverse 
rugulae. Pedicel and gaster densely and finely punctate, with more scattered, larger 
piligerous punctures. Legs and genitalia shining. 

Hairs fulvous brown, long, dense, and erect on the head and upper portions of 
thorax and pedicel, sparser on the pleurae and legs; on the gaster much shorter and 
sparser and hardly more than a dilute, suberect pubescence. Outer genital valves 
and free edge of hypopygium with numerous hairs. 

Ferruginous brown; gaster, genitalia, legs and antennse somewhat paler. Wings 
like those of the female. 

Texas: Chapel Hill, Brenham, La Grange, Ye Gua Creek (Lincecum); 
Austin (Buckley, Lincecum, Townsend, McCook, Wheeler); Alice, New 
Braunfels, Elgin, Granite Mountain (Wheeler). 

There exists some confusion in the literature in regard to this species. 
The European myrmecologists, Mayr, Forel and Emery, have confounded 
it with a closely related, but in my opinion, perfectly distinct Mexican species, 
A. mexicana F. Smith (.4. fervens Say). The soldiers and mediae of the 
latter, of which I possess specimens from Guadalajara (J. F. McClendon), 
Irapuato (C. H. T. Townsend), Esquinapa (J. H. Batty), Cuernavaca and 
Queretaro (Wheeler), differ from the corresponding phases of texana in 
having the head smooth, shining and hairless above. In the male the 
hypopygium (PI. L, Fig. 25) is shorter, distinctly excised in the middle 
with the blunt teeth further apart, and without a median fenestra. The 
outer genital appendages are slender and taper to a sharp point; the middle 
pair are more slender and flattened, less geniculate and more uniformly 
curved. In PI. L, Figs. 21-25 are given camera drawings of the male 
hypopygia of all the species o{ Atta s. str. except columbica (which is probably 



1907.] Wheeler, Fungus-growing Ants of North America. 703 

a variety of cephalotes), because, as Mayr has shown in his work on the 
Formicidse of the Novara Expedition, this scelerite and the genital append- 
ages furnish excellent characters for distinguishing the species. 

2. Atta mexicana (F. Smith). 

The name of this species, which is not known to occur in Texas, though 
it is widely distributed in Mexico at an altitude of 5,000 to 7,000 feet, must 
either be attributed to Drury, and not, as has usually been done, to Say, or 
if, as Dalla Torre maintains, the Formica jervens of Drury is merely a syn- 
onym of A. cephalotes, we must adopt A. mexicana F. Smith as the, name 
of the Mexican form. As it seems to me to be impossible to determine the 
species to which Drury's female specimen belonged, I believe that the name 
mexicana should be adopted. The synonymy disentangled from that of ^4. 
texana would then read as follows : 

? Formica jervens Drury, Illustr. Nat. Hist,, III, 1782, p. 58, pi. 42, fig. 3.' 9 . 

Atta jervens Say, Boston Journ. Nat! Hist., I, 3, 1836, p. 290, 9 . 

CEcodoma mexicana F. Smith, Catalog. Hymen.' Brit. Mus., VI, 1858, p. 185, no. 

9 9. PL X, fig. 20. . . 

(Ecodoma Mexicana Norton, Amer. Natur., II, 1868, p. 66, pi. I, figs. 9 and 10. 

(Ecodoma mexicana Norton, Proc. Essex Inst., VI, 1868, Comm. p. 9, fig. $ 9 . 
? (Ecodoma mexicana Moreno, Naturaleza, III, 1876, pp. 189-190. 
Atta jervens Leconte, Writings of Th. Say., Entom., II,, 1859, p. 734. 
Atta jervens Mayr, Reise der Novara, 11, 1. Formicidae, 1865, p. 81, Q 9 d' ■ 
Atta jervens Forel, -Bull. Soc. Vaud. Sc. Nat., XX, 1884, p. 47 (in part). 
Atta jervens Dalla Torre, Catalog. Hymen., VII, 1893; pp. 152, 153 (in part). 
Atta tmvigata Pergande, Proo. Calif. Acad. Nat. Sci. (2), V, 1895, p. 896, $ . 
Atta jervens Forel, Biol. Centr.-Am., Hymen., IH, 1899-1900, p. 33 (in part), 
Atta jervens Forel, Ann. Soc. Ent, Belg., XLV, ISOl, p, 124; (J . 
Atta jervens Wheeler, Ann. Soc. Ent. Belg., XLV, 1901, p. 200, 5. 

3. Atta (Moellerius) versicolor Pergande. 

Atta versicolor Pergande, Proc. Calif. Acad. Sci. (2), IV, 1893, pp. 31, 32, 5. 
Atta {Acromyrmex) versicolor Emery, Zool, Jahrb., Abth. f, Syst,, VIII, 1894, p, 

330, 5, . 

Atta versicolor Fenner, Entom, News, VI, 1895, p, 215, 
Atta (Acromyrmex) versicolor Forel, Biol. Centr,-Am,, Hymen:, III, 1899-1900, p, 

36, $, . . 

Atta {Mcellerius) versicolor Emery, R, Accad, Sci, 1st, Bologna, April 1905, pp, 108, 

111, a. , ■ ' 

IForfcer, (PL XLIX, Fig. 5.) Length: 2.3-6 mm. 

Head without the mandibles broader than long, in larger specimens somewhat. 



'704 Bulletin American Museum of Natural History. , [Vol. XXIII; 

narrowed in front, broadly and obtusely excised behind, with rounded posterior 
corners and slightly convex sides. Eyes convex, less than J the distance from the 
anterior to the posterior comers. Mandibles rather convex, with seve;ral blunt 
teeth. Clypeus concave in the middle, with two very short, blunt teeth on the 
anterior margin. Frontal carinas with expanded, toothed lobes in front. Frontal 
area obsolete. Antennal scapes reaching to the posterior corners of the head, some- 
what incrassated towards their tips. Lateral carinse with a short, acute tooth. Post- 
ocular spines absent; anterior and superior occipital regions with a number of short 
teeth or spines; posterior occipital region with a longer acute spine on each side. 
Pronotum with a pair of short, downwardly directed inferior and a pair of long, robust 
and acute superior spines directed for>vard and outward. Mesonotum with two 
pairs of spines, the anterior about half as long as the superior pronotal pair, but 
more rapidly tapering and directed upward and backward; the posterior pair smaller 
and closer together. Epinotum with two spines which are nearly as long as the 
superior pronotal pair but more slender and directed backward, upward and slightly 
outward. Petiole longer than broad, its node subrectangular, with four equidistant, 
subequal teeth in a transverse row. Postpetiole nearly twice as broad as the petiole, 
broader than long, concave above, with six short bidentate spines, four in a trans- 
verse anterior row and two behind and more widely separated at their bases. Gaster 
broadly elliptical, broadest behind the middle; basal segment with a median longi- 
tudinal depression, on each side of which there are several acute tubercles, longest 
near the anterior and lateral margins. 

Mandibles shining, coarsely punctate and striate; remainder of body, including 
the legs arid scapes, opaque, densely punctate. Head, thorax, pedicel and anterior 
border of gaster vermiculately or reticulately rugulose. Basal gastric segment with ■ 
scattered, shallow foveolte.- 

Hairs brown or tawny, suberect, not very abundant, rather short, curved or 
hooked on the body, straighter on the scapes and legs. 

Ferruginous brown; borders of mandibles and anterior border of clypeus black. . 

Female. Length: 8 mm. 

Head resembling that of the worker, but the posterior corners are more acute 
and the antennal scapes are longer. Pronotum with two broad and rather blunt 
inferior and two acute superior spines, which are directed forward and outward. 
Scutellum trapezoidal with bidentate posterior edge. Epinotal spines long, curved 
and diverging, of nearly uniform thickness up to their rapidly tapering tips which 
are bent downwards. Petiole and postpetiole similar to those of the worker, but 
the median pair of teeth in the former longer than the lateral pair and the spines on 
the postpetiole reduced- to small teeth. Gaster pyriform, with the first segment 
flattened above and without the pointed tubercles. 

Mandibles and legs shining; remainder of body opaque. Head coarsely, densely 
and crenately rugose, the rugae being longitudinal on the sides but diverging from 
the front and median line on the upper surface. Thorax covered with rugae similar 
to those on the head, transverse on the pronotum, longitudinal on the mesonotum 
and pleurae, and irregular on the scutellum. Pedicel and gaster densely and irregu- 
larly rugulose; on the middle of the first segment of the latter the rugula; are ihore 
regular and longitudinal. Antennal scapes and legs coarsely punctate and more 
or less roughened. 

Pilosity like that of the worker. 



1907.] Wheeler, Fungus-growing Ants of North America. 705 

Ferruginous brown; upper surface of head, mesonotum and gaster blackish, 
the mesonotum with a V-shaped red spot on the middle and the gaster with a pair 
of elliptical ferruginous spots on the basal segment. Wings opaque yellowish 
brown, with dull yellow veins. 

Male. (PL L, Fig. 26.) Length: 8 mm. 

Head, without the mandibles and eyes, as long as broad, subrectangular, with 
nearly straight posterior border. Eyes large, protruding, hemispherical, with their 
posterior orbits at the middle of the head. Mandibles well-developed, acute, flat- 
tened and multidentate. Clypeus very faintly and sinuately excised in the middle. 
Frontal and lateral carinae without teeth. Antennal scapes extending fully § their 
length beyond the posterior comers of the head. The latter with a small, acute 
superior and a broad flattened inferior tooth on each side. Pronotum with a 
larger inferior and much smaller superior tooth on each side. Mesonotum with 
distinct Mayrian furrows. Scutellum with a median longitudinal depression and 
a pair of blunt posterior teeth. ' Epinotum with short, convex base and longer 
straight declivity; spines like those of the female but more slender and tapering 
more gradually. Petiole and postpetiole like those of the female, the former with, 
small acute teeth above and three lateral teeth, the latter with four teeth on each 
side. Gaster broadly elliptical, with the basal segment flattened above and without 
tubercles. Genital appendages convex, curved inward, with broad, rounded, sub- 
truncate tips. Legs slender. 

Body including the mandibles and legs, opaque; gaster slightly shining. Man- 
dibles finely striated and coarsely punctate. Head, thorax and pedicel densely rugu- 
lose, the rugulfe being longitudinal on the head, mesonotum, scutellum, pleurae and 
epinotum, and transverse on the pronotum, petiole and postpetiole. Gaster and 
legs densely punctate. Genital appendages with a few scattered foveolae. 

Pilosity like that of the worker and female. 

Black; mandibles, border of clypeus, frontal carinse; neck, antennae, coxae, 
tibiae, tarsi and gaster ferruginous brown, posterior borders of gastric segments 
and genitalia somewhat paler. Wings like those of the female. 

Arizona: Tucson (Fenner, Wheeler); Yucca (Wheeler). 

Mexico: Calamujuet, Lower Cahfornia (Eisen and Haines); Sonora 
(Coll. Am. Mus. Nat. Hist.). 

The types are from Calamujuet; the above description is drawn from 
Tucson specimens. 

4. Atta (Mcellerius) versicolor chisosensis subsp. nov. 

A number of workers taken by Judge O. W. Williams in the Chisos 
Mountains of southw^estern Texas, and a few workers taken by myself at 
Terlingua in the same region, represent a distinct subspecies. 

They differ from the typical versicolor in their distinctly lighter and more 
yellowish color, much less pronounced sculpture and in having only a few 
(about 12) pointed tubercles on each side of the median gastric depression, 

[Sept., 1907.'] is 



706 Bulletin American Museum of Natural History. [Vol. XXIII, 

whereas in the typical form there are two or three times as many. Owing 
to their feebler sculpture the workers of chisosensis are throughout much 
more shining than the typical form. 

5. Atta (Trachymyrmex) septentrionalis McCook: 

1 0Scodoma virginiana Buckley, Proc. Ent. Soc, Phila., VI, 1867, p. 346, no. 61, i^. 
? CEcodoma tardigrada BtrcniLEY, Proc. Ent. Soo. Phila., VI, 1867, p. 349, no. 65, ^ . 

9 d'. 
Atta septentrionalis McCook, Proc. Acad. Nat. Sci. Phila., 1880, pp. 359-363, Fig. g . 
Atta (Acromyrmex) tar'digrada Forel, Bull. Soc. Vaud. Sci. Nat. (2) XX, p. 91, 1884, 

p. 358, 9 d^. ■ ■ 
Atta tardigrada May'e, Verh. zool. hot. Ges. Wien, XXXVI, 1886, p; 442. 
Atta {Trachymyrmex) tardigrada Fobel, Ann. Soc. Ent. Belg., XXXVII, 1893, p. 

601. 
Atta tardigrada Dalla Tobrb, .Catalog. Hymen., VII, 1893, p. 154. 
Atta tardigrada var. sepfentrionoKs, Catalog. Hymen., VII, 1893, p. 154. 
Atta {Trachymyrmex) tardigrada Emery, Zool. Jahrb., Abth. f. Syst,, VIII, 1894, 

p. 329. 
Atta {Trachymyrmex) tardigrada Fobel, Rivista Sci. Biol., II, 1900, p. 9. 
Atta {Trachymyrmex) tardigrada Forel, Ann. Soo. Ent, Belg., XLV, pp. 396, 397. 
Atta {Trachymyrmex) septentrionalis Wheeler, Trans. Tex, Acad. Sci., IV, Pt. II, 

no. 2, 1902, pp. 13, 14. 
Atta {Trachymyrmex) septentrionalis Wheeler, Psyche, June, 1903, p. 101, Fig. 

6b. 
Atta {Trachymyrmex) septentrionalis Whebleb, Bull. Am. Mus. Nat. Hist., XXI, 

1905, pp. 386, 387. 

Worker. (PL XLIX, Fig. 4.) Length: 2.0-3 mm. 

Head, without the mandibles, about as broad as long, a little broader behind 
than in front, with obtusely excised posterior border, somewhat rounded posterior 
angles and rather straight sides. Eyes not very prominent, more than J the distance 
from the anterior to the posterior comers of the head. Mandibles with two larger 
acute apical and 7 or 8 small basal teeth. Anterior border of clypeus sinuately 
excised in the middle. Frontal area triangular, obsolescent. Frontal earinse with 
flattened, rounded lobes in front, continued back as a pair of diverging ridges beyond 
the middle of the head as far as but not meeting the lateral carina. Antennal 
• scapes extending about J their length beyond the posterior corners of the head, some- 
what thickened towards their tips. Region between the frontal carinte and posterior 
corners of the head covered with small acute tubercles, one pair of which on the 
posterior corners is longer and bidentate. Pronotum with a pair of blunt, down- 
wardly directed inferior spines, two long acute superior spines and between these in 
the middle a pair of short bidentate spines or tubercles, which, are closer to each 
other than to the lateral tubercles. Mesonotum with two pairs of blunt spines. 
Mesoepinotal constriction pronounced. Epinotum with four longitudinal rows of 
tubercles, the inner continued back into the bases of a pair of acute spines which 
are directed upward, backward and outward and are from J to § as long as the 
slightly convex base of the epinotum. Declivity sloping, forming in profile an ob- 



1907.] Wheeler, Fungus-groioing Ants of North America. 707 

tuse angle with the base. The upper surface of the thorax and all the spines, with 
the exception of the inferior pronotal pair are covered with small tubercles. Petiolar 
node from above nearly square, a little broader than long; in profile its anterior 
surface is flattened, its summit acute and furnished with a pair of teeth. On each 
side of these there is also a small blunt tooth. Postpetiole about as broad as the 
epihotum, somewhat more than twice as broad as the petiole, and distinctly broader 
than long, subpentagonal from above, concave in the middle behind and covered with 
small tubercles. Gaster pyriform, broadest behind the middle; first segment with 
a faint, longitudinal, median depression and a short ridge on each lateral border. 
The dorsal surface is covered rather uniformly with small, acute tubercles, as are 
also the antennal scapes. 

Mandibles and anterior border of clypeus faintly shining or glossy, the former 
finely and densely striated. Remainder of body and appendages opaque and indis- 
tinctly granular. 

Hairs brownish yellow, short, hooked, more or less erect and not very abundant, 
usually arising from the small tubercles and covering the body and appendages 
rather uniformly. 

Body ferruginous brown, legs slightly paler, mandibular teeth black, front and 
vertex dark brown; gaster in many specimens with a broad longitudinal fuscous or 
blackish stripe on the middle of the first segment. 

Female.. Length: 3.8-4 mm. 

Head resembling that of the worker. Pronotum besides the blunt, downwardly 
directed inferior spines, with a pair of strong, somewhat flattened, acute superior 
spines directed outward and somewhat forward. Scutellum semioircularly excised 
and bidentate behind. Epinotal spines long, of rather uniform thickness to within 
a short distance of their acute, rapidly tapering tips. Pedicel and gaster as in the 
worker, but the lateral teeth of the petiole are smaller and blunter and the posterior 
margin of the postpetiole is excised. AVings 4 mm. long. 

Sculpture similar to that of the worker; mesonotum and scutellum covered 
with rows of small elongated tubercles. 

Like the worker also in pilosity and coloration. Head with a large black spot 
on the ocellar region and the gastric stripe is deeper and more distinct, but not 
reaching the anterior border of the basal segment. Wings blackish with veins of the 
same color; costal cell yellowish. 

Male. Length: 3-3.5 mm. 

Head but little broader behind than in front, broadest in the region of the eyes, 
with slightly convex posterior border. Eyes convex, posterior orbits at the middle 
of the head. Mandibles like those of the worker but smaller. Clypeus with broad, 
entire anterior margin. Frontal carinje lobed in front, uniting behind with the lateral 
-carinse, which are furnished with a small tooth in the middle. Posterior corners of 
head with several small, acute spines or teeth. Antennse slender; scapes somewhat 
thickened distally and surpassing the posterior corners by about J of their length. 
Pronotum with small acute superior and inferior teeth. Mesonotum -mih. well- , 
developed Mayrian furrows. Scutellum similar to that of the female. Epinotum 
with subequal base and decUvity; spines slender, acute, diverging, bent downward 
at their tips, their bases continued forward as a pair of crenated ridges on to the 
base of the epinotum. Petiole and postpetiole like those of the worker, but the 



708 Bulletin American Museum of Natural History. [Vol. XXIII, 

latter segment without distinct tubercles. Gaster elliptical, con^'ex above, the first 
segment with smaller and more scattered tubercles than in the worker and female, 
and without a median longitudinal impression. Outer genital appendages broad 
and short, with rounded edges; median pair with straight, slender, pointed tips. 
Hypopygium entire, with a broad, rounded point in the middle. Legs long and 
slender; terminal tarsal joint not enlarged. 

Opaque, mandibles and clypeus granvilar; head and thoracic dorsum coarsely, 
pleurae, petiole and postpetiole more finely reticulate-rugose. Epinotum and gaster 
finely reticulate or granular. Legs smoother and somewhat shining. 

Pilosity similar to that of the worker and female. 

Ferruginous brown; upper surface of head, thorax, pedicel and first gastric 
segment more or less blackened; legs and posterior borders of gastric segments 
yellowish; antennal scapes dark brown. Wings as in the female. 

Texas: Austin, Montopolis, Milano (Wheeler); Denton (W. H. Long); 
Paris (Miss A". Rueker, C. T. Brues). 

Florida: (Mrs. Mary Treat, T. Pergande), Miami and Jacksonville 
(Wheeler). 

District of Columbia: Washington (Pergande, Swingle). 

North Carolina: Black Mountain (Forel). 

New Jersey: Vineland (Mrs. Treat); Toms River (Morris, McCook); 
Lakehurst (Wheeler, W. T. Davis); Lucaston (E. Daecke); Miltown 
and Manusquam (Davis). 

I believe that Buckley's name fardigrada, which has been very generally 
applied to this species, should be rejected and replaced by McCook's septen- 
trionalis, first, because Buckley's description will apply equally well to this 
or the following species or even to Mycetosoritis hartmanni, although his 
account of the nests applies to none of these but rather to a small colonyof 
Atta texana; and second, although Forel wrote in 1884 that Mayr had in 
his possession a type specimen of Buckley's tardigrada which made it possible 
to refer Florida specimens received from Mrs. Treat to this species. Dr. 
Mayr writes me (March 24, 1902); "Ich besitze von Atta (Trachymyrmex) 
tardigrada keinen Buckley'schen Typus." There is no possible means of 
ascertaining just Vfhat species Buckley described. McCook's description 
is equally worthless, but his specimens were redescribed by Forel, so that 
the name septentrionalis must stand. The above description is drawn 
from specimens taken early in May from a single colony at Montopolis, 
near Austin, Texas. Forel regarded McCook's specimens as representing 
a variety of the southern form, but Emery failed to distinguish any varietal 
differences betwjeen southern and northern specimens. A number of workers 
taken by me at Lakehurst, New Jersey are larger (3.4-3.6 mm.) than speci- 
mens from Texas and Florida and are of a paler, more yellownsh color with 
a darker and more distinct gastric stripe. A dealated female from Lake- 



1907.] Wheeler, Fungus-growing Ants of North America. ' 709 

hurst and a winged individual from Lucaston, New Jersey agree in having 
a dark spot on the middle of the pronotum, one on the postpetiole and in 
having the infuscation of the head and middle of the gaster more extensive. 
If we regard the New Jersey specimens as representing the typical form of 
the species it will be necessary to distinguish the darker southern form as a 
variety, for which I would suggest the name obscurior var. nov. 

6. Atta (Trachymyrmex) turrifex Wheeler. 

Wheeler, Psyche, June, 1903, pp. 100-102, fig. 6a, 9 . 

Worker. (PI. XLIX, Fig. 3.) Length: 3-3.75 mm. 

Head without the mandibles a little longer than broad, slightly broader behind 
than in front, with obtusely excised posterior border, rather straight sides and promi- 
nent posterior angles. Eyes convex, in front of the middle of the head. Mandibles 
pointed, 7-8-toothed. Clypeus sinuately and rather deeply excised in the middle. 
Frontal area triangular, indistinct. Frontal carinae with large round anterior lobes, 
somewhat concave in the middle, and continued back as a pair of diverging ridges 
nearly as far as the posterior corners of the head, but not meeting the almost equally 
long lateral cariuEe. Antennae robust; scapes reaching only to the posterior corners 
and fitting into deep grooves between the frontal and lateral carinse. Upper surface 
of head, with the exception of these grooves, covered with tubercles, two pairs of 
which on the superior and inferior portions of the occipital corners are larger than 
the others and bidentate. Scapes covered with similar but smaller tubercles. 
Pronotum on each side with an acute downwardly directed inferior spine; above 
with a pair of rather long, acute lateral spines and a shorter bifurcated median spine. 
Mesonotum with two pairs of thick blunt spines. Mesoepinotal constriction very 
pronounced. Epinotum with subequal base and decUvity at right angles to each 
other in profile; the former convex, the latter concave; spines acute, nearly as long 
as the base, directed upward, backward and outward and prolonged forward at 
their bases as a pair of subparallel, crenated ridges lying between a shorter pair of 
similar lateral ridges. All the thoracic spines, with the exception of the inferior 
pronotal pair, are covered with small tubercles. Similar tubercles are also scattered 
over the dorsal surface of the thorax between the spines. Petiole from above as 
broad as long, nearly square, with a transverse row of four equidistant tubercles 
across its middle and connected with the median pair by longitudinal ridges. There 
is another pair near the posterior edge of the segment. Postpetiole twice as broad 
as the petiole and nearly twice as broad as long, impressed in the middle behind and 
covered with small tubercles. Gaster suboblong, with straight anterior border and 
subparallel sides, a little broader behind than in front, convex above and below; 
first segment with longitudinal ridges half way down its sides, a faint median and 
two lateral depressions. Its whole surface is covered with small tubercles which 
are connected with one another by a net-work of indistinct ridges. Legs stout, and 
as far as the second tarsal joint, covered with tubercles which are somewhat smaller 
than those on the body. 

Mandibles with shining, coarsely striatopunctate tips, and opaque, finely striated 
bases. Remainder of body opaque, obscurely granular and more or less rugulose. 



710 Bulletin American Museum of Natural History. [Vol. XXIII, 

Hairs brown, hooked, suberect, covering the body and appendages, except the 
antennal funiculi which are clothed with a very fine whitish pubescence. 

Ferruginous brown; front and vertex dark brown, legs somewhat paler than the 
body. In old specimens the body is darker in color and the roughened portions are 
overlaid with a bluish bloom. 

Female. Length: 4-4.5 mm. 

Head resembling that of the worker. Pronotum with short, acute inferior and 
superior spines, the latter not flattened. Scutellum with two long, blunt teeth and 
a deep median excision in its posterior border. Base of epinotum barely half as 
long as the declivity, which is concave; spines long, stout and rather blunt. Pedicel 
and gaster similar to those of the worker; posterior border of the postpetiole entire. 
Wings 6 mm. long. 

Sculpture similar to that of the worker. Mesonotum and scutellum with indis- 
tinct longitudinal rows of small tubercles; remainder of thorax granular, with minute, 
scattered tubercles. 

Pilosity and color like those of the worker. Wings opaque brown, with darker 
veins. 

Texas: Austin, Montopolis, Marble Falls, Fort Stockton, Paisano Pass, 
Marfa, Del Rio, Langtry (Wheeler). 

The worker of this species may be readily distinguished from that of 
septentrionalis by the more pointed posterior corners of the head, the much 
shorter antennal scapes which do not extend beyond the ]30sterior corners, 
the unpaired pronotal spine, and the rougher legs and gaster. The female 
turrijex is distinguished by several of these characters and also by the much 
longer and paler wings. 

7. Atta (Trachymyrmex) arizonensis sp. nov. 

Female (dealated). (PI. XLIX, Figs. 9 and 10.) Length: 4.75 mm. 

Head, without the mandibles, as broad as long, somewhat broader behind than 
in front, with straight sides, obtusely excised posterior margin and rather pointed 
posterior corners. Eyes moderately convex, in front of the middle of the sides. 
Mandibles with two larger apical and several smaller basal teeth. Anterior border 
of clypeus sinuately iiotohed in the middle. Frontal area triangular, indistinct. 
Frontal carinse with large reflected and rather angular lobes, without rounded impres- 
sions in their surfaces, continued back as diverging ridges nearly to the posterior 
corners of the head, but not meeting the much shorter lateral carinse. Antennal 
scapes distally enlarged, extending about \ their length beyond the posterior corners 
of the head. The latter with numerous conical tubercles, two. of which on the . 
inferior occipital angles are somewhat larger than the others and double. Pronotum 
with two small, flat, lappet-like inferior spines and a pair of long, but not compressed 
superior spines, directed outward and slightly forward. Posterior border of scutel- 
lum with a broad median excision and a pair of bliint teeth. Base of epinotum 
sloping, about half as long as, the concave declivity. Spines short, acute, a little 
longer than broad at the base, directed backward and outward. All the spines of 



1907.] Wheeler, Fungus-growing Ajita of North America. 711 

the thorax, excepting the inferior pronotal pair, covered with tubercles. Petiole 
from above oblong, slightly longer than broad, with bidentate anterior angles, and 
a pair of longitudinal dorsal ridges elevated into short spines or teeth at their anterior 
ends. Postpetiole more than twice as broad as the petiole, somewhat broader than 
long, transversely elliptical, with the sides produced in the middle in the form of 
short double spines; posterior margin semicircularly excised and somewhat reflected; 
upper surface with a pair of irregular elevations and numerous small tubercles. 
Gaster subspherical, but little longer than broad, anterior border straight, first seg- 
ment obtusely ridged on the sides anteriorly, .without a median depression and uni- 
formly covered with small tubercles which are somewhat larger on the dorsal than 
on the ventral side. Legs well-developed and, like the antennal scapes, covered 
with small tubercles. 

Mandibles somewhat shining, finely striated at their bases, more coarsely towards 
the inner edges of the blades. Remainder of body opaque, granulate-rugulose; 
rugulffi on the sides of the head and between the lateral and frontal carinae longitudi- 
nal and minutely and irregularly tuberculate, on the front converging from each 
side towards the median line. On the thorax the rugulse are irregularly longitudinal, 
more regularly on the mesonotum and scutellum where they are interrupted by low 
tubercles. Postpetiole and first gastric segment, especially at its base, obscurely 
and longitudinally rugulose. 

Hairs dark brown, short, hooked or curved, suberect, uniformly covering the 
body and appendages. Antennal funiculi with very fine whitish pubescence. 

Ferruginous brown, front and vertex darker, mandibular teeth black. AVhole 
surface of body bluish pruinose. 

Male. Length: 4.5 mm. 

Head, without the eyes, somewhat longer than broad, a little broader behind 
than in front, with straight posterior border. Posterior orbits at the middle of the 
head. Mandibles well-developed, with two larger, acute apical and several small 
basal teeth. Clypeus \rith entire, broadly rounded anterior . border. Frontal 
carinse with well-developed anterior lobes and short posterior ridges which bend 
around laterally and pass over into the lateral carinse, thus enclosing two elliptical 
facial cavities. Antennse slender, scapes slightly thickened distally and reaching 
more than J their length beyond the posterior comers of the head. Posterior corners 
with short, acute spines, those on the superior and inferior angles being somewhat 
larger than the others. Inferior and superior pronotal spines very small and acute. 
Mayrian furrows of mesonotum distinct but shallow. Scutellum like that of the 
female. Epinotum with base somewhat shorter than the oblique declivity; spines 
rather short, somewhat longer than broad at the base, as long as the base of the epino- 
tum, acute, directed backward and slightly outward, covered with small tubercles. 
Petiole similar to that of the female but concave in the middle and traversed by four 
longitudinal tuberculate ridges. Postpetiole less than twice as broad as the petiole, 
and nearly twice as broad as long, subpentagonal, with broadly excised posterior 
border and covered with tubercles. Gaster elliptical, convex above, covered uni- 
formly with small acute tubercles except in the middle line near the base. Outer 
genital valves short and broad, with rounded tips; median pair terminating in a 
straight, attenuate point. Hypopygium entire, very bluntly pointed in the middle. 
Legs long and slender, covered with very small and rather indistinct tubercles. Last 
tarsal joints enlarged. . 



712 Bulletin American Museum of Natural History. [Vol. XXIII, 

Mandibles subopaque, very finely and indistinctly striated. Body and appen- 
dages opaque. Facial cavities granular; dorsal porti(5ns of head, mesonotum, 
' paraptera and scutellum coarsely and reticulately rugose. Remainder of body 
coarsely granular, the pronotum, pleura3 and epinotum also more or less irregularly 
rugulose. 

Hairs fulvous, similar to those of the female. 

Black or dark brown; mandibles, clypeus, anterior corners of head, funiculi, 
thoracic sutures, tarsi, knees and tips of tibiffi, genitalia and posterior and lateral 
borders of the gastric segments fulvous. Wings blackish, with yellowish costal 
cell and brown veins. 

Arizona: Palmerlee, Cochise County, Aug. 24 (C. Schaeffer). 

Described frona a single female and six males. 

This species is clearly distinct though in certain respects it is intermediate 
between T. septentrionalis and turrifex. The female differs from that of 
turrijex in the longer antennal scapes, which surpass the posterior corners 
of the head, and the posteriorly excised postpetiole, and from both this and . 
septentrionalis in its much heavier sculpture, the greater size of the pronotal 
spines and the shape of the gaster, which is not oblong and impressed in the 
middle.- 

8. Atta (Trachymyrmex) jamaicensis Em. Andre. 

Atta (Acromyrmex) jamaicensis Ebn. AndrJs, Rev. d'Entora., Juillet, 1893, p. 149, 

. S- ■ ' ■ . ' 

Trachymyrmex sharpii Forel, Trans. Bnt. Soc. London, 1893, Pt. IV, Deo. pp. 372, 

373, $. 

Atta (Trachymyrmex) maritima Wheeler, Bull. Am. Mus. Nat. Hist., XXI, 1905, 

pp. 107-109, pi. vii, figs. 7 and 8, ^ . 

Worker. Length: 3.5-4.5 mm. 

Head, without the mandibles, as broad as long, somewhat broader behind than 
in front, with obtusely -excised posterior border, rather acute posterior angles and 
slightly convex sides. Eyes somewhat flattened, in front of the middle of the head. 
Clypeus with a small sinuate notch in the middle of its anterior border. Frontal 
area triangular, indistinct. Frontal carina with broad subtriangular lobes in front, 
their surfaces not impressed in the middle, continued back as a pair of diverging 
ridges to the posterior corners where they meet the postorbital ridges thus enclosing 
elongated grooves for the antennal scapes. Vertex with a pair of blunt projections 
and short rows of small tubercles. Each posterior corner of the head with three 
short blunt spines at the angles of an equilateral triangle. Antennae slender, scapes 
somewhat enlarged -towards their tips which surpass by less than J their length the 
posterior comers. Pronotum with a blunt, lappet-shaped inferior and a long pointed 
superior spine on each side. In the middle between the two. spines is a small double 
tubercle. Mesonotum with a pair of robust and rather blunt anterior and a pair of 
small acute posterior spines. Mesoepinotal constriction long and rather shallow. 
Epinotum with subequal base and declivity meeting, almost at a right angle, the 



1907.] ■ Wheeler, Fungus-growing Ants of North America. . 713 

former convex in profile, the latter straight; spines long, acute and rather slender, 
distinctly shorter than the base of the epinotum, directed obliquely upward, backward 
, and outward and continued forward as a pair of blunt, subparallel ridges on the 
base of the epinotum. All the thoracic spines, except the inferior pronotal pair, 
covered with small tubercles. Petiole from above oblong, shghtly longer than 
broad, abruptly narrowed anteriorly into a short peduncle; node with four 
equidistant acute teeth. Postpetiole trapezoidal, more than twice as broad as 
the petiole, as long as the petiole, as long as broad, semicircularly impressed 
in the middle behind but with straight, entire posterior border. The border 
of the impressed region and the sides beset with, small tubercles. Gaster suboblong, 
slightly broadest behind the middle, narrowed in front; first segment with promi- 
nent lateral ridges and three broad longitudinal depressions on the dorsal surface. 
Tubercles small and acute, absent in the median depression and on the ventral sur- 
face. Legs long and like the antennal scapes covered with small tubercles. 

Mandibles with shining, coarsely punctate blades, more opaque and finely 
striated at the base. Remainder of body and appendages opaque, granular. 

Hairs brownish, very short and curved, longer on the anterior and inferior por- 
tions of the head and legs than on the body. Pubescence whitish, very fine and 
dilute, confined to the antennal funiculi. 

Black; mandibles, except the teeth, thorax, petiole, and postpetiole ferruginous 
or yellowish; pleurae more or less clouded with black or fuscous; antennse, legs and 
apex of gaster dark brown, middle portions of femora and tibije often blackish. 

Female. Length: 4.5-5 mm. 

Head similar to that of the worker. Pronotum with rather blunt inferior and 
long and pointed superior spines, which are directed outward and forward and 
slightly upward. Scutellum convex, its posterior edge excised in the iniddle and 
with a pair of acute, laterally compressed teeth. Epinotum with short convex 
base and longer flattened declivity; spines long, slender and acute, directed back- 
ward and somewhat outward. Petiole, postpetiole and gaster like those- of the 
worker, but the first broadest in the middle and constricted behind and the second 
without tubercles on its upper surface. Wings 6 mm. long. 

Surface of body coarsely granular; front and vertex rugulose; mesonotum with 
longitudinal rows of small tubercles. 

Pilosity like that of the worker, but longer on the thorax and gaster. 

Head and gaster very dark brown; thorax, pedicel, mandibles, antennae and 
legs paler, ferruginous. Pleurje, two triangular spots on the anterior border of the 
mesonotum, an oblong blotch on the middle of the same region behind, the parap- 
tera- and anterior comers of the scutellum, black or dark brown. Wings smoky 
brown with darker veins and yellowish costal cell. 

Male. Length: 3.5-4.2 mm. 

Head small, without the eyes and mandibles nearly as broad as long, with 
rounded and constricted posterior and very prominent ocellar region. Eyes large 
and convex, their posterior orbits at the middle of the head. Mandibles acute, 
denticulate, but rather feeble. Clypeus with straight, entire anterior border. 
Antennae very slender; scapes surpassing the posterior corners of the head by about 
h their length. Pronotum with very small, acute superior spines and the inferior 
spines reduced to angles on the lower border of the segment. Mesonotum and 
scutellum convex', the former with distinct but shallow Mayrian furrows, the latter 



714 Bulletin American Museum of Natural History. [Yol. XXIIl, 

with a pair of small acute teeth on the posterior border. Epinotum with short, 
convex base and longer sloping and concave declivity; spines short, acute, not 
longer than the base and hardly longer than broad at their insertions. Petiole and 
postpetiole like those of the worker, but the former narrowed behind the middle and 
the latter with more obscure tubercles. Gaster elliptical, broadest in the middle 
taperjng behind, without depressions and ridges on the first segment and with very 
minute piligerous tubercles on both the dorsal and ventral surfaces. Genitalia 
small and retracted. ' Legs very slender, without tubercles; terminal tarsal joint 
slightly enlarged. Wings large, 5.5 mm. long. 

Whole body and appendages .opaque, minutely granular; head finely and 
longitudinally rugulose behind. Mesonotum with longitudinal rows of shallow 
oblong depressions or foveola;. Mesopleurae feebly rugulose. 

Hairs like those of the worker and female, but finer, straighter and more appressed 
: on the legs and antennae. 

Dull, rather light ferruginous; posterior portion of head, Mayrian furrows, 
lateral borders and a large oblong spot on the posteromedian portion of the mesono- 
tum, paraptera and sides of the scutellum black. Wings like those of the female. 

West Indies: Jamaica (T. D. A. Cockerell); St. Vincent (H. Smith); 
Andros and New Providence Is., Bahamas (Wheeler); Culebra (Wheeler). 

I believe there can be no doubt that Forel's T. sliarpi, Andre's jamaicen- 
sis and my maritima are all the same species. I have recently found in the 
collection of the Philadelphia Academy of Sciences a few workers from 
Jamaica, which agree very closely with Andre's description and with my 
specimens of maritima from the Bahamas. These, in turn^ are almost 
identical with specimens collected from a greater number of colonies in the 
island of Culebra. Prof. Forel, to whom specimens from the latter locality 
w^ere sent, pronounces them to be "indistinguishable from small specimens 
of sharpi." Andre's name jamaicensis must stand, however, as his descrip- 
tion was published some six months earlier than Forel's. So far as known, 
therefore, there is only a single widely distributed species of Trachymyrmex 
in the West Indies, although there is an allied form {T. uricjii Forel) in 
Trinidad and a subspecies of this {juscatus Emery) and several distinct 
species of the subgenus on the adjacent South American continent. 

T. jamaicensis is readily distinguished from all of our North American- 
species by the peculiar coloration of the worker and female, the structure of 
the frontal and postorbital carinee, the shape of the petiole and postpetiole, 
etc. The male is peculiar in coloration, the shape of the head, and in having 
very small, concealed genitalia. 

9. Atta (Mycetosoritis) hartmanni subgen. et sp. nov. 

Worker. (PI. XLIX, Figs. 6 and 7.) Length: 1.8-2 mm. 

Head, without the mandibles, longer than broad, but little broader behind than 



1907.] Wheeler, Fungus-growing Ants of North. America. 715 . 

in front, with broadly and obtusely excised posterior margin, subparallel sides and 
rather acute posterior corners. Eyes moderately convex, just in front of the middle 
of the head. Mandibles convex, with two large, acute apical and several small and, 
indistinct basal teeth. Clypeus moderately convex, with entire, broadly rounded 
anterior margin. Frontal area large, triangular, distinct. Frontal carinte with 
very large, broad, flattened lobes anteriorly overlapping the insertions of the antennae. 
These lobes have acute anterolateral corners and are separated by distinct reentrant 
angles from the posterior ridges which are straight, diverging and continued back to 
the posterior corners of the head. Lateral carinas continued back only a little behind 
the eyes where they turn in but fail to meet the frontal carinse, though leaving a 
marked groove for the accommodation of the scape and extending to the posterior 
corner. Antennae robust, scapes somewhat thickened distally, reaching with their 
tips to the posterior corners. Thorax long and stout, especially in front, though 
decidedly narrower than the head. Pronotum without inferior spines, with a pair 
of obtuse spines at the humeral angles and a pair of tubercles in the middle almost 
as far apart as each is from ^a lateral spine. Mesonotum with a blunt ridge on each 
side, somewhat higher in front and behind than in the middle. These ridges con- 
verge rapidly behind and just in front of the deep mesoepinotal constriction. Epi- 
notum in profile with subequal base and declivity, the former convex, especially in 
front, with a pair of ridges diverging posteriorly and continued into the small rather 
blunt spines, which are but little longer than broad at their bases, and directed up- 
ward, backward and outward. Epinotal declivity sloping, concave. Petiole from 
above suboblong, broader than long, a little broader behind than in front where it 
is suddenly constricted into a short peduncle; node above with a pair of rather acute 
teeth. Postpetiole IJ times as broad as the petiole, broader behind than in front, 
sides slightly rounded, posterior border angularly excised in the middle. Gaster 
suboblong, broader behind than in front, not impressed in the middle above, anterior 
and lateral borders straight, the latter with indistinct longitudinal ridges. Legs 
rather long and stout. 

Opaque throughout;- mandibles very finely striated, especially at the base. 
Body very finely granular; front and vertex longitudinally rugulose; first gastric 
segment covered uniformly with minute tubercles. 

Hairs whitish, suberect, curved and short on the body and appendages, longer 
and more conspicuous on the clypeus and mandibles. 

■ Ferruginous brown; upper surface of head more or less blackish. 

Female. Length: 2.5-2.7 mm. 

Head resembling that of the worker, anterolateral corners of frontal carinae 
mbre acute; ocelli very small and indistinct. Pronotum large, with a pair of stout, 
acuminate superior spines directed forward, outward and upward. Mesonotum 
small, elliptical, flattened, somewhat narrowed in front, with distinct but shallow 
Mayrian furrows. Scutellum as long as broad, with excised posterior border and 
acute posterior angles. Epinotum with short, convex base, long concave and verti- 
cal declivity and short spines directed backward and outward. Petiole, postpetiole 
and gaster resembling those of the worker. Wings short (2 mm.) and rounded; 
venation like that of Trachymyrmex and Cypho7nyrmex but with the inner branch 
of the cubital and the distal segment of the externomedian veins very faint or obso- 
lete. . . 

Like the worker in sculpture, pilosity and coloration, but with the mesonotum 



716 Bulletin American Museum of Natural History. [Vol. XXIII, 

longitudinally rugulose. Scutellum and paraptera darker than the remainder of 
the thorax. Wings opaque, fuscous;, yellowish towards the base and costal margin. 

Male. (PI. XLIX, Fig. 8.). Length: 2 mm. 

Head, without the eyes and .mandibles, but httle longer than broad, broader 
behind than in front, with flattened occipital region and a longitudinal ridge on each 
side of the rather acute posterior comers. Eyes large and convex, the posterior 
orbits a little behind the middle of the head. Mandibles like those of the worker 
in shape but smaller and feebler. Clypeus with entire, rounded anterior margin. 
Lobes of frontal carinse similar to those of the worker but erect; their posterior ridges 
short and meeting the lateral earinte. Scapes very short, extending only a little 
distance beyond the posterior corners of the head; funicular joints cylindrical, joints 
1-7 less than twice as long as broad, terminal joints somewhat longer. Prohotum- 
with short, acute superior spines; inferior spines absent. Mesonotum with distinct 
Mayrian furrows. Paraptera produced posteriorly as short teeth. Scutellum like 
that of the female. Epinotum with subequal base and declivity, the former convex, 
the latter concave; spines about half as long as the base, blunt, somewhat curved, 
directed upward and outward. Petiole and postpetiole like those of the worker, 
but the former proportionally longer, the latter broader. Gaster elliptical, median 
genital appendages digitiform, with blunt tips. Hypopygium with entire rounded ' 
posterior margin. Legs rather stout; terminal tarsal joints not enlarged. 

Opaque; mandibles and gaster faintly shining; the former very finely, the body 
more coarsely and densely punctate. Head, thorax and postpetiole also irregularly 
reticulate-rugulose; first gastric segment above with minute, acute and uniformly 
distributed tubercles. 

Hairs like those of the worker; more distinct and scattered on the gaster. 

Head, thorax and pedicel black; first gastric segment very dark brown; remain- 
ing gastric segments, mandibles, antenna and legs light brown or yellowish, antennal 
scapes, coxEe, and middle portions of the femora infuscated. Wings like those of 
the female. 

Texas: Montopolis and Delvalle, near Austin (Wheeler). 

This species which I take pleasure in dedicating to my former pupil, 
Mr. C. G. Hartmann, who aided me in excavating' the nests of this and 
other Texan Attii, may be regarded either as a degenerate and simplified 
Trachymyrmex or as an aberrant Cyphomyrmex. It resembles the species 
of Trachymyrmex in its form and pilosity, while it approaches the species of 
Cyphomyrmex in its small size, the very large lobes of the frontal carinse, the 
reduction of the cephalic and thoracic spines and the absence of tubercles 
on the greater portion of the body. In 1887 (Verb. zool. bot. Ges. Wien, 
XXXVII pp. 561, 562) MajT described an aberrant female Attiine ant from 
Brazil as Cyphomyrmex asper, which, though considerably larger than the 
above described species, would seem nevertheless to belong to the same sub- , 
genus. More recently Emery (Bull. Soc. Ent. Ital., XXXVI, 1905, pp. 162, 
163) has described and figured a single worker specimen from Chubut, 
Argentina, as dubiously referable to Mayr's species. This specimen meas- 



1907.] Wheeler, Fungus-growing Ants of North America. 717 

ures 3 mm. in length and has no reentrant notch between the anterior lobular 
and posterior ridge-like portions of the frontal carinse, and the shape of the 
thorax appears to differ considerably from that of hartmanni. Emery, to 
whom I sent some workers of this latter form, says, however, that both 
species "connetano tra loro i generi Atta e Cyphomyrmex; e dubbio a quale 
dei due convenga megiio assegnarli." As I shall show in the latter part of 
this paper, the habits of hartmanni are much more like those of Trachymyr- 
mex than Cyphomyrmex, so that the subgenus Mycetosoritis, which I have 
erected for this species and aspera Mayr, belongs rather with Atta s. lat. M. 
hartmanni should be regarded as the type of this subgenus as Mayr's species 
is so imperfectly known. 

10. Atta (Mycocepunis) smithi Forel. 

Atta {Mycocepurus) smithii Fokel, Trans. Ent. Soc. London. 1893, p. 370. ^ . 

Worker. (PL XLIX, Figs. '15 and 16.) Length: 2.2-2..5 mm. 

Head, without the mandibles, slightly longer than broad, a little broader in 
front than behind, with obtusely excised posterior border, pointed posterior corners 
and rather convex sides. There is a distinct though shallow occipital groove. Eyes 
moderately convex, just behind the middle of the head. Mandibles narrow, acute, 
with oblique, 5-toothed blades. Clypeus short and broad, with entire, nearly 
straight anterior border. Frontal carinse with small rounded lobes, very close to- 
gether and separated only by a narrow, cuneate groove; they are continued behind 
as low diverging ridges which fade away before reaching the posterior corners. 
-Postorbital carinse indistinct, reaching the posterior corners but not including with 
the frontal ridges distinct grooves for the accommodation of the antennal scapes. 
Scapes much shorter than the funiculi, slightly thickened towards their tips, which 
barely surpass the posterior corners of the head. Thorax long, in front about f as 
broad as the head, with deep mesoepinotal constriction. Pronotum without inferior 
spines, above with tour upwardly directed spines arranged in an arc with its convexity 
directed forward; the two outer spines longest and each with a small acute tooth in 
front of its base; the inner pair of spines small. Mesonotum also with an arc of four 
spines but with its convexity directed backward, so that the spines on both segments 
form a broad ellipse. The anterior mesothoracic spines are longer than the posterior 
pair. There is also a pair of small projections close together near the anterior borders 
of the mesonotum and in the middle of the ellipse. Epinotum with the base fully 
twice as long as the declivity, the former with four successive pairs of spines, the 
first and third very short and acute, the second longer and the fourth, representing 
the typical epihotal spines of other Attii, fully as long as the declivity, slender, 
pointed, directed upward and slightly backward and outward, curved inward at 
their tips. Metasternum with a small blunt tooth on each side. Petiole from above 
narrow, fully twice as long as broad, somewhat violin-shaped, broader behinrl than 
in front, constricted just in front of the node which is cuboidal, with a concave sur- 
face and each of the four upper corners produced into a small spine. In profile its 
upper surface is horizontal, its anterior slope long and concave. Postpetiole nearly 
four times as broad as the petiole and nearly as broad as long, campanulate, with 



718 Bulletin American Museum of Natural History. [Vol. XXIII, 

four longitudinal ridges of which the median pair are blunter and separated by a 
longitudinal groove deepening suddenly at the posterior margin of the segment to 
form a somewhat circular pit. Gaster much smaller than the head, fully J longer 
than broad, widest posteriorly, with straight sides and anterior border and acute 
anterior angles. The first segment has a sharp longitudinal ridge on each side but 
no median depression. Legs long and rather stout. 

Opaque throughout; mandibles very finely striated; jhead above irregularly 
reticulate-rugose, more coarsely behind than in front. Remainder of body and 
appendages very finely and obscurely punctate-granular and faintly reticulate, 
except the gaster which is more distinctly and evenly punctate and slightly roughened 
on its upper surface. Legs and scapes also slightly scabrous. 

Hairs yellowLsh; veiy short, curved and sparse, subreclinate, most distinct on 
the ga ter and appendages. Pubescence very fine, whitish, confined to the antennal 
funiculi. 

Yellowish ferruginous; upper surface of head and gaster and the ridges and tips 
of the spines darker. Mandibular teeth black. 

St. Vincent: Bellisle (H. H. Smith). 

Cuba. 

I have redescribed this species from a type specimen kindly sent me by 
Professor Forel who has also described a closely related species, M. gmldii, 
from Brazil. The subgenus Mycocepurus, as Forel has shown, is related 
to the other subgenera of Atta on the one hand and to Cyphomyrmex and 
Myr7nicocrypta on the other. It is peculiar and aberrant, however, in its 
small size, its small, closely approximated frontal lobes and spinulation. 
Hitherto M. smithi has been Imown only from St. Vincent. I have received 
specimens from Cuba. Among the materials in my collection I find also a 
number of workers from two other localities and representing the following 
varieties : 

11. Atta (Mycocepurus) smithi var. borinquenensis var. nov. 

Porto Rico: Vega Baja, Arecibo, Utuado, Monte Mandios (Wheeler). 

The workers of this form resemble the type verj^ closely in size, coloration 
and sculpture but have on each side of the occipital furrow at the postero- 
median border of the head, a distinct tooth which is nearly as large as the 
teeth which form the posterior corners. The posterior epinotal spines are 
curved inward at their tips as in the type. 

12. Atta (Mycocepurus) smithi var. tolteca var. nov. 

Mexico: Tuxpan, Jalisco (-J. F. McClendon). 

Closely resembling the type, but of a yellow color and with straight, 
more acute and more erect posterior epinotal spines and feebler cephalic 



1907.] Wheeler, Fungus-growing Ants of North America. 719 

sculpture. The two median occipital teeth of horinquenensis are represented 
by low, pointed ridges. 

13. Cyphomyrmex rimosus Spinola. 

Cryptocerus ? rimosus Spinola, Mem. Acoad. Sci. Torino (2), XIII, 1851, p. 65 no. 

49, 5 d'. 
Cryptocerus rimosus F. Smith, Trans. Ent. Soc. London (2), II, 7, 1854, p. 223, no. 28. 
Meranoplus difformis F. Smith, Catalog. Hymen. Brit. Mus., VI, 1858, p. 195, no. 

7, §. 
Cryptocerus rimosus F. Smith, Trans. Ent. Soc. London (3), I, 4, 1862, p. 409, no. 

11, §• 
Meranoplus difformis F. Smith, Trans. Ent. Soo. London (3), I, 4, 1862, p. 413, 

no. 7, g. 
Cyphomyrmex deformis Mayb, Verb. zool. hot. Ges. Wien, XXXVII, 1887, p. 558, 

§ 9 c? (in part). 
Cyphomyrmex rimosus Dalla Torre, Catalog. Hj^men., VII, 1893, p. 150 (in part). 
Cyphomyrmex rimosus Emery, Bull. Soc. Ent. Ital., XXVI, 1894, pp. 88, 89. 
Cyphomyrmex rimosus Urich, Trinidad Field Nat. -Club, II, no. 7, 1895, p. 181. 
Cyphomyrmex rimosus Fokel, Biol. Centr.-Am., Hymen., Ill, 1899-1900, p. 40. 

The typical form of this widely distributed and variable species appears 
to be confined to northern South America and the adjacent mainland of 
Central America and Mexico. It is represented in my collection by a few 
worker and female specimens from Grenada, Nicaragua (C. T. Baker) and 
a number of workers from Manatee, British Honduras (J. D. Johnson). 
In these specimens the postpetiole of the worker is less than twice as broad 
as long and the color is of a rich yellowish brown, with the head and posterior 
portion of the gaster clouded with dark brown. In the female the post- 
petiole is scarcely broader in proportion to its length and has a perfectly 
straight posterior border. According to Emery the male has a relatively 
narrow head, with very acute posterior angles and the postpetiole is less 
than IJ times as broad as long.- A single worker in my possession from 
Hayti (P. J. Schmitt) approaches the typical rimosus more closely than the 
Central American specimens, as its thoracic protuberances are longer and 
more acute and the postpetiole is only IJ times as broad as long. The 
following variety, according to Emery {in litteris), approaches the typical 
rimosus very closely except in its darker color. 

14. Cyphomyrmex rimosus var. comalensis var. nov. 

Worker. (PI. XLIX, Fig. 1.) Length: 1.8-2 mm. 

Head, without the mandibles, longer than broad, much narrower in front than 
behind, with obtusely excised posterior margin and rather sharply angular posterior 



720 Bulletin American Museum of Natural History. [Vol. XXIII, 

corners. Eyes moderately convex, near the middle of the head. Mandibles small, 
5-toothed. Clypeus short on the sides, with a triangular median portion which has 
a rounded, raised and entire anterior border. Behind it is wedged in between the 
frontal earinse which are dilated in front to form two large horizontal lobes impressed 
in the middle, rounded on the sides, bluntlj^ angular in front and separated at the 
■ level of the eye by a reentrant angle from the posterior ridges. These diverge and 
extend to the posterior corners of the head where they meet the postorbital ridges 
and form with them rounded ear-like lobes. Each postorbital ridge is furnished 
\^'ith a blunt but distinct tooth just behind the eye. The frontal and postorbital 
ridges enclose a deep groove for the accommodation of the antennal scape. Vertex 
of head with a pair of low, rounded elevations. Antennal scapes robust, thickened 
towards their tips which extend a little beyond the posterior corners of the head; 
funiculi slender at the base; joints 2-8 slightly broader than long. Prpnotum with 
four blunt protuberances above in a transverse row, the lateral pair larger and more 
angular, the inner pair small and closer together than to the lateral pair. Meso- 
notum a little longer than broad, broader in front than behind, on each side with a 
blunt ridge, nearly interrupted in the middle so that in certain lights the mesonotum 
seems to bear two pairs of blunt, elongated elevations. Mesoepinotal constriction 
very short and rather deep. Epinotum with a convex base, which is considerably 
shorter than the sloping, flattened declivity, and with a pair of anteriorly converging 
ridges. The spines are represented by very small, blunt elevations at the posterior 
ends of these ridges. Petiole somewhat more than twice as broad as long, flattened 
above, with rounded sides, only f as broad as the postpetiole, which is twice as broad 
as long, convex in front and -snth a feeble excision in its posterior border. In front 
of this excision there is a distinct elongate median depression. Gaster suboblong, 
somewhat longer than broad, with a very short and indistinct median depression 
at the anterior border. Legs long and stout; hind femora bent and angularly 
dilated near the base on the flexor side. 

Opaque throughout; mandibles very finely and densely striated; remainder of 
body minutely granular. 

Hairs white, short, scale-like, appressed and uniformly distributed, more slender 
on the legs than on the body. Pubescence very fine, whitish, coniined to the man- 
dibles and funiculi. • . ' 

Very dark brown, upper surface of head and gaster black, anterior portions of 
the frontal lobes, antennal scapes and tibise dark brown; remainder of legs, funiculi 
and mandibles light brown. 

Female. Length: 2.2-2.4 mm. 

Head very similar to that of the worker. Pronotum with pointed inferior 
angles at the coxal insertions, and above with a pair of blunt angular projections 
which are as broad at their bases as long. Mesonotum anteriorly with a longitudinal 
median depression and distinct Mayrian furrows, so that its surface is separated 
into four slightly convex, elongated areas, two anterior and two posterolateral. 
Epinotum with very short, convex base and long, abrupt and concave declivity; . 
spines blunt, laterally compressed, shorter than broad at their bases. Scutellum 
flattened, broader than long; its posterior margin excised in the middle and pro- 
duced as a broad tooth on each side. Pedicel, gaster and legs similar to those of the 
worker, but the postpetiole nearly three times as broad as long, with nearly straight 
posterior border. 



1907.] Wheeler, Fungus-groioing Ants of North America. 721 

Like the worker in sculpture and pilosity. 

Head, postpetiole, gaster and appendages colored as in the worker. Thorax 
dark brown, mesonotum and scutellum blackish, each of the convex areas of the 
former with a reddish brown spot. AVings opaque, smoky brown, with pale veins. 

Male. Length: 2.3 mrn. 

Head, including the eyes, about as broad as long, with straight posterior border 
and acute posterior angles. Eyes large and convex, in front of the middle of the 
head. Ocelli projecting. Mandibles rather slender, with two apical and no basal 
teeth. Clypeus convex, with very faintly notched anterior border. Lobes of 
frontal carinas like those of the worker but erect- posterior ridges obsolete. Antennae 
slender; scapes suddenly thickened towards their tips and surpassing the posterior 
corners of the head by nearly J their length; funicular joints cylindrical, less than 
twice as long as broad except the four terminal joints which are longer; first funicular 
joint thicker than the others. Thorax similar to that of the female but much more 
slender; basal surface of epinotum longer; spines short and rather acute. Petiole 
and postpetiole like those of the worker, but the former segment is proportionally 
longer and the latter has the median depression further forward. Gaster elliptical, 
slightly flattened; first segment in front with a narrow, faintly impressed line. 
Genitalia retracted. Legs slender; hind femora without a triangular projection 
on the flexor side. 

Opaque; gaster finely shagreened and distinctly shining. 

Appressed white hairs less scale-like and conspicuous than in the worker and 
female, especially on the gaster; very short on the legs and antennal scapes. 

Coloration similar to that of the worker; terminal gastric segments, legs and 
antennae dull yellowish brown. Wings as in the female. 

Texas: Sources of the Comal River at New Braunfels (Wheeler). 

15. Cyphomyrmex rimosus var. fuscus Emery. 

Emery, Bull. Soo. Ent. Ital.,XXVI, 1894, p. 89, $ 9 d^. 

In this variety, described from Santa Catharina, Brazil, all three phases 
are "entirely brown; mandibles, funiculi and articulations reddish; stature 
a little more robust" than the typical form. 

16. Cjrphomyrmex rimosus var. major Forel. 

FoREL, Ann. Soo. Ent. Belg. XLV, 1901, p. 125. §. 

In the worker of this variety from Guatemala the stature is somewhat 
larger (2.7-2.8 mm.) than that of the typical form, the ear-like corners of 
the head longer and the thoracic ridges and projections more prominent. 



722 Bulletin American Museum oj Natural History. [Vol. XXIII, 



17. Cyphomyrmex rimosus minutus Mayr. 

Cyphomyrmex minutus Mayr, Verh. zool. bot. Ges. Wien, XII, 1862, p. 691 no. 1 § . 
Cataulacus deformis Roger, Berl. entom. Zeitschr., VII, 1863, p. 210, no. 104, $ cJ*. 
Cyphomyrmex steinheili Fokel, Bull. Soo. Vaud. Sc. Nat. (2) XX, 91, 1884, p. 368, 

. S- ' . ■ 

Cyphomyrmex deformis Mayk, Verh. zool. bot. Ges. .Wien, XXXVIII, 1887, p. 558, 

5 ? (J (in part)'. 

Cyphomyrmex rimosus Dalla Torre, Catalog. Hymen., VII, 1893, p. 150 (in part). 

Cyphomyrmex rimosus Forel, Trans. Ent. Soc. London, 1893, Pt. IV, p. 374. 

Cyphomyrmex rimosus subsp. minutus Emery, Bull. Soo. Ent. Ital., XXVl, 1894, 

p. 89, 5 c?.. ■ ■ , 

Cyphomyrmex rimosus Forel, Biol. Centr.-Am., Hymen., Ill, 1899-1900, p. 40 

(in part). 
Cyphomyrmex rimosus subsj). minutus Wheeler, Bull. Am. Mus. Nat. Hist., XXI, 

1905, p. 106, figs. N. and 0. 

Venezuela: Cayenne (Emery). 

West Indies: Cuba (Mayr); St. Vincent (H. H. Smith); New Provi- 
dence, Bahamas (Wheeler); Culebra and Porto Rico (Wheeler). 

Florida: Planter, Key Largo (Wheeler). 

This subspecies which is confined to the West Indies and adjacent shores 
of North and South America, appears to differ very slightly from the typical 
form of the species and the var. comalensis. The worker is somewhat 
smaller and often of a paler color, with the thoracic projections more feebly 
developed and more rounded and the vestiges of the epinotal spines even 
more insignificant. Both the petiole and postpetiole are considerably 
broader, each being fully twice as broad as long. According to Emery the 
rrtale of minutus has the head rounded behind, but my specimens from the 
Bahamas and Porto Rico have the posterior border of the head straight and 
the posterior angles projecting as acute teeth. In the female the epinotum 
is very steep, with small, blunt spines. Forel seems never to have accepted 
this subspecies, and I am myself very doubtful whether it deserves to rank 
as such. It is certainly much less distinct and less easily recognizable than ■ 
the following: 



18. Cyphomyrmex rimosus dentatus Forel. 

Cyphomyrmex rimosus race dentatus Forel, Ann. Soo. Ent. Belg., XLV, 1901, p. 124 

Cyphomyrmex rimosus subsp. dentatus Wheeler, Ann. Soo. Ent. Belg., XLV, 1901, 
p. 200. 



1907.] Wheeler, Fungus-growing Ants of North America. 723 

Mexico: Cuernavaca (Wheeler). 

The worker of this marked subspecies is described by Forel as fohows : 
"Differs from the type in that the basal surface of the epinotum has two 
distinct teeth. The pronotal protuberances are stronger, more dentiform. 
The occipital ears arc a little more pronounced than in the type of the species, 
and especially form a more complete and larger groove for the scape which 
surpasses them little if at all. Entirely pale ferruginous yellow, with the 
front and vertex indistinctly brown. The petiole is also broader. The 
postpetiole has a strong median notch at the middle of its posterior border 
and its sides are prolonged as dentiform cones which are curved backward. 
The sculpture is that of rimosus, but the gaster has a distinct but very fine 
system of minute, blunt tubercles. The pubescence is extremely short 
and very fine, not dilated nor brilliant, so that it is inconspicuous." 

Two dealated females of dentatus in my collection measure 2.4 mm. in 
length, and have prominent but blunt and upturned prothoracic spines 
and strong laterally compressed epinotal teeth; the epinotal dechvity is 
very concave, the posterolateral cones of the postpetiole are more prominent 
and the median dorsal region of the same segment is more concave than in 
the worker. The head and thorax are much rougher than in the females 
of the typical rimosus and the gaster is more strongly tubercular, with a 
short but deep median depression at the base of the first segment. The 
body is dark brown, the upper surface of the head and thorax blackish and 
covered with a bluish bloom. 

19. Oyphomyrmex rimosus transversus Emery. 

Cyphomyrmex rimosus subsp. transversus Emery, Bull. Soc. Eiit. Ital., XXVI, 1894, 

p. 90, § Q (?. 
Cyphomyrmex dentatus race olindanus Forel, Ann. Soc. Ent. Belg., XLV, 1901, p. 

337, §. 
Cyphomyrmex rimosus transversus Emery, Bull. Soc. Ent. Ital., XXXVIII, 1905, p. 

161, 5 9 d'. , , . . ■ 

Brazil: Matto Grosso (Emery); Ceara an'dOlinda (P. J. Schmitt). 

The worker of this subspecies resembles 'clerdhtu's in sculpture and in the 
development of the thoracic projections, but-thfe appressed hairs on the 
body are broader and more scale-like even than in the typical rimosus, 
the petiole and postpetiole broader, and the median dorsal impression on 
the latter and on the base of the first gastric segment deeper and longer. 
The epinotum has blunt but distinct teeth. 

In the female the epinotal teeth are very large, compressed and obtuse, 
the pedicel even broader than in the worker. 



724 Bulletin American Museum of Natural History. [Vol. XXIII, 

The male has the posterior border of the head broadly excised and the 
posterior corners with acute, slightly recurved teeth. Except in pilosity 
transversus is closely' related to dentatus, as Forel has observed. 

20. Cyphomyrmex rimosus salvini Forel. 

Cyphomyrmex rimosus race salvini Forel, Biol. Centr.-Am., Hymeii., Ill, 1899- 
1900, p. 40, pi. iii, fig. 2. 9 . 

Forel described only the female of this form from a specimen taken at 
Bugaba, Panama. The late Dr. F. C. Paulmier brought me from Port 
Limon, Costa Rica two males and several workers which seem to me to 
belong to this same form. The worker is larger than that of any of the other 
subspecies of rimosus, measuring nearly 2.5 mm. The frontal lobes are 
very large and concave, the ear-like corners of the head much prolonged and 
pointed. The,, thoracic projections, especially the anterior pronotal pair, 
are long arid acute, the epinotal teeth, very faintly indicated. The petiole 
is more than twice as broad as long, the postpetiole about IJ times as broad 
as long, with excised posterior margin and a posteromedian irupression. 
There is also a distinct median impression at the base of the gaster. The 
hairs are much flattened and scale-like, pearly white and abundant, appresscd 
on the body, but reclinate or even suberect on the legs and scapes. The 
body is light chocolate brown, the legs and antennse paler. 

The female according to Forel's description, measures 3.7 mm. and is 
very similar to the worker in the shape of the head. The superior pronotal 
teeth are stout and triangular, the epinotal teeth much reduced. The 
postpetiole is proportionally broader than in the worker, the gaster very 
convex, feebly marginate on the sides and without any indications of de- 
pressions and elevations. 

The male, too, is decidedly larger than the corresponding sex in other 
forms of rimosus, measuring nearly 3 mm. in length. The superior occipital 
teeth are short and acute, the superior pronotal pair blunt and rather slender. 
In the place of the spines, the epinotum has a pair of broad, laterally com- 
pressed projections, which are continued forward and backward on the 
base and declivity as prominent ridges. The hairs, on the body and append- 
ages are all appressed and not very abundant, not dilated on the legs and 
only slightly scale-like on the body. The latter is chocolate brown like 
that of the worker, with the first gastric segment blackish, the mandibles, 
clypeus, frontal lobes, antennse, legs, terminal gastric segments and genitalia 
dull yellow. The wings are very dark brown or blackish. 



1907.1 Wheeler, Fungus-growing Ants of North America. 725 



21. Cyphomyrmex wheeleri Forel. 

FoRBL/BuU. Soc. Ent. Suisse, X, 7, 1900, pp. 282-284, {^ $ . 

Worker. (PL XLIX, Fig. 2.) Length: 2.-2.5 mm. 

Head, without the mandibles, longer than broad, broader behind than in front, 
with obtusely excised posterior margin and rather sharp, ear-lilie posterior corners. 
Eyes moderately large, convex, at the middle of the head. Mandibles acute, with 
five sharp teeth. Clypeus with thin, entire anterior border. Frontal area triangular. 
Frontal carinse with large, rounded anterior lobes, each with a circular impression, 
and continued back as a pair of strong, straight, diverging ridges to the posterior 
corners, where they loop around and become continuous with the postorbital carinas , 
thus enclosing deep grooves for the antennal scapes. Each postorbital carina bears 
a prominent tooth Just behind the eye. Vertex with a pair of short longitudinal 
ridges as far apart as each is from the posterior ridge of a frontal carina and con- 
tinued laterally along the occipital border to the posterior corner. Here also the 
'ears' are joined by a pair of prominent ridges from the posteroinferior surface of the 
head. Antennal scapes very slender at the base, enlarged towards the tips which 
reach the posterior corners of the head; joints 2-8 of the funiculus a little broader 
than long. Pronotum with a pair of acute inferior teeth and above with a larger 
pair of angular humeral projections and a median pair of smaller projections. Meso- 
notum elevated in the middle in the form of an elongate elliptical, slightly concave 
disc, truncated behind, with a faint transverse depression on its posterior portion 
and bordered with a prominent ridge which is interrupted in the middle in front. 
Mesoepinotal constriction short and deep. Epinotum as high as the mesonotum, its 
base very convex and nearly as long as the concave declivity with which it forms an 
obtuse angle in profile. Spines laterally compressed, short and triangular, as broad 
at the base as long, directed backward and continued forward and backward as 
ridges on the base and declivity. There is also a pair of lateral ridges on the base. 
Petiole nearly twice as broad as long, as broad in front as. behind, with rounded 
anterior angles; node short, compressed anteroposteriorly, with two spines, directed 
upward and backward. Postpetiole trapezoidal, IJ times as broad as the petiole 
and less than twice as broad as long, with two blunt anterior, two larger and more 
rounded posterior protuberances and a broad, longitudinal depression in the middle; 
posterior border entire. Gaster suboblong, distinctly longer than broad, as broad 
in front as behind; first segment convex above, with distinct lateral ridges and a 
faint median depression at the base. Tibiae somewhat compressed; hind femora 
curved, angularly dilated and compressed near the base on the flexor side. 

Opaque throughout; mandibles very finely and indistinctly striated. Remainder 
of body very finely granular-punctate; antennal grooves and gaster densely and 
distinctly punctate. 

Hairs short, glistening white, scale-like and appressed, uniformly distributed 
over the appendages and upper surface of the body. Pubescence very fine, whitish, 
confined to the antennal funiculi. 

Yellowish ferruginous; mandibular teeth black. 

Female. Length: 2.5-2.7 mm. 

Very similar to the worker. Pronotum with prominent inferior and superior 
teeth, the former acute, the latter larger and blunt. Mesonotum prominent, flat- 



726 Bulletin American Museum of Natural History. [Vol. XXIII, 

tened, with a faint median furrow anteriorlj' and a pair of broader Mayrian furrows. 
Scutellum with very broadly and faintly excised posterior border separating a pair 
of broad, acute teeth. Epinotum with the base convex and only about half as long 
as the abrupt concave declivity; spines similar to those of the worker but somewhat 
stouter. 

Sculpture and pilosity as in the worker. 

Color a little darker in old specimens. Wings opaque, infuscated; the mem- 
branes and veins in the anterobasal portion of both fore and hind wings fulvous. 

Male. Length: 2.4-2.6 mm. 

Head, without the mandibles and eyes, narrow, longer than broad, with straight 
posterior border. Mandibles like those of the worker but less distinctly denticulate. 
Frontal carinse with large, reflected lobes and strong, diverging posterior ridges 
reaching to the posterior corners where each terminates in a compressed, projecting 
tooth. Postorbital carinEe absent. Antennce slender, scapes enlarged towards 
their tips which surpass the posterior corners of the head by about J of their length. , 
Pronotum with indistinct inferior, but prominent and acute superior teeth. Meso- 
notum with distinct Mayrian furrows. Scutellum like that of the female, but with 
more deeply excised posterior border. Petiole and postpetiole like those of the 
worker and female. Gaster elliptical, convex above. Legs long and slender. Hind 
femora not angularly dilated below. 

Opaque; very finely and densely punctate; gaster faintly shining or glossy. 

Pilosity very similar to that of the worker and female. 

Ferruginous; upper surface of head and the thoracic depressions blackish; 
basal segment of gaster dark brown above. Mandibles, antenniE, legs and tip of 
gaster yellowish. ' Wings like those of the female. 

Texas: Austin, Belton, Langtry, Fort Davis (Wheeler). 

California: Three Rivers (Culbertson). 

The types from which the worker and dealated female were carefully 
described by Forel, -are from Austin. The species is allied to the South 
American C. strigatus Mayr and C. aiiritus Mayr but difl'ers from both in 
having larger frontal lobes and in lacking prominent ridges on the middle 
of the first gastric segment. The ear-like posterior corners of the head are 
much shorter than in auritu.s and the scapes are shorter than in strigatus. 

22. Cyphomyrmex flavidus Pergande. 

Cyphomyrmex flavidus Pergande, Proo. Calif. Acad. Sci. (2), V, Dec. 1895, p. 895, i^ . 
Cyphomyrmex flavidus Fohel, Biol. Centr.-Am., Hyrnen., Ill, 1899-1900, p. 41. ■ 

Worker. Length: 2.2-2,8 mm. 

Head, without the mandibles, longer than broad, broader behind than in front, 
with obtusely excised posterior border and prominent posterior corners. • Eyes con- 
vex, at the middle of the head. Mandibles small and acute, with oblique, apparently 
5-toothed blades. Clypeus long and rather flat, with a minute median excision in 
its thin anterior border. Frontal area triangular. Lobes of frontal carina; very 



1907.] Wheeler, Fungus-growing Ants of North America. 727 

large, horizontal, half as long as the head and extending out laterally a little beyond 
the borders of the head. Posteriorly each of these lobes has a deep subtriangular 
depression in its surface. The ridges of the frontal carinte diverge backward to the 
posterior corners where they pass over into the postorbital carinae, not through a 
rounded arc but rectangularly, so that the termination of the antennal groove is 
broad and truncated. There is a ridge on each side of the inferior occipital portion of 
the head and a pair of projections on the vertex, which are continued laterally along 
the occipital border as a pair of blunt ridges to the posterior corners. Antennal 
scapes enlarged towards the tips, which extend a little beyond the posterior corners; 
joints 2-7 of the funiculus a Httle broader than long. Thorax robust; pronotum 
with a pair of acute inferior teeth, which are directed forward, and a blunt protuber- 
ance on each side above. Mesonotum in the form of an elevated, elliptical and 
slightly concave disc, bordered with a low ridge which is interrupted in the middle 
behind and in the middle on each side. This ridge bears a pair of rounded swellings 
jiist in front of its lateral interruptions. Mssoepinotal constriction deep and narrow. 
Epinotum with a pair of swellings at its base; declivity sloping, longer than the 
base; spines reduced to a. pair of laterally compressed and rather acute teeth which 
are as long as they are broad at the base. Petiole and post petiole resembling each 
other in shape, the former twice as broad as long, broader behind where its sides are 
produced as a pair of blunt angles; it is flattened above, without spines or teeth and 
with a small semicircular impression in the middle of its posterior border. Post- 
petiole J broader than the petiole, more than twice as broad as long, rounded in 
front, with a median groove, broadening behind; posterior margin with three semi- 
circular impressions of which the median is the largest. Gaster longer than broad, 
suboblong, with straight, feebly marginate sides, rounded anterior and posterior 
borders, and a short median groove at the base of the first segment. Hind femora 
curved, with an angular, compressed projection near the base on the flexor side. 

Opaque throughout, very finely and densely punctate-granular. 

Hairs minute, appressed, slightly dilated, glistening white, rather sparse and 
indistinct. Pubescence fine, whitish, confined to the antennal funiculi. 

Ferruginous yellow; clypeus, frontal lobes, front and middle of vertex more or 
less browTiish; mandibular teeth black. 

Mexico: Santiago Ixtquintla, Tepic (Eisen and Vaslit). 

This species, which I have redescribed from a type specimen kindly 
sent me by Mr. Pergande, at first sight closely resembles C. wheeleri. It 
may be distinguished, however, by the absence of teeth on the petiole, the 
much broader and more truncated ear-like corners of the head, longer 
antennal scapes and much blunter ridges and projections on the thorax. 
G. flavidus is thus intermediate in several respects between wheeleri and 
rimosus, but is undoubtedly a distinct species. Although at present known 
only from northern Mexico, it may be expected to occur as far north as the 
southern portions of Arizona and California. 



/ 728 Bulletin American Museum of Natural History. [Vol. XXIII, 



23. Myrmicocr3fpta brittoni sp. nov. 

Worker. (PI. L, Figs. 18 and 19.) Length: . 2.3-2.5 mm. 

Head, without the mandibles, about as broad as long, slighi;ly broader behind 
than in front, with obtusely excised posterior border, rather straight sides, rounded 
posterior corners and a narrow median longitudinal groove. Eyes distinctly in 
front of the middle, of moderate size and convexity. Mandibles large, convex, 
with straight outer and inner borders, the latter with about ten teeth which grow 
gradually smaller towards the base. Clypeus short, with entire, flattened and very 
broadly rounded anterior border. Frontal carince with flattened but slightly 
reflected lobes, which are much longer than broad, with roundly angular external 
edges reaching only half the distance between the median line and the external border 
of the head. Mesially these lobes are fused with the posterior portion of the clypeus 
and enclose the small, indistinct frontal area which is triangular and longer than 
broad. The lobes of the frontal carinse are not continued behind in the form of 
diverging ridges as in other Attii. Lateral carinas sharp and distinct, continued to 
the posterior orbits and bounding a broad, short and deep antennal groove. There 
are no postorbital carina. Antennse rather slender; scapes slightly curved at the 
base and enlarged towards their tips, which slightly surpass the posterior corners 
of the head; funicular joints all considerably longer than broad, terminal joint 
nearly as long as the four preceding joints together. Thorax long and rather nar- 
row, in front about f as broad as the head. Pronotum with small, acute inferior 
angles. There is a pair of blunt epinotal teeth, but otherwise the thorax is smooth 
and without spines or projections. Mesoepinotal constriction distinct, but long 
and rather shallow. Humeral angles rounded, mesonotum about as long as the 
pronotum, elongate elliptical, flattened, slightly higher than the epinotum. Epino- 
tum with subequal base and declivity, the former straight and horizontal, the latter 
-concave and sloping, without longitudinal ridges. Metastemimi with a small 
rounded tubercle on each side. Petiole oblong, a little broader than long, with 
slightly rounded anterior and acute posterior corners; node evenly convex above, 
suddenly constricted anteriorly into a very short peduncle. Postpetiole nearly 
twice as broad as the petiole, somewhat broader than long, with- straight posterior 
border, rounded anterior corners and straight, subparallel sides; convex and evenly 
rounded above without a posteromedian impression. Gaster smaller than the 
head, longer than broad, elliptical, with straight anterior border and convex upper 
surface, without lateral ridges or median impression on the first segment. Legs 
slender, hind femora straight and without an angular projection on the flexor side. 

Opaque throughout; mandibles slightly glossy, very finely and densely striated; 
■remainder of body very densely and uniformly punctate. 

Hairs short, glistening white, dilated and scale-like, appressed, uniformly dis- 
tributed over the body and appendages. Antennal funiculi and tarsi with delicate 
whitish pubescence. 

Black; clypeus, antennal grooves, inferior comers of pronotum, antennal scapes, 
coxae and legs, dark brown; mandibles, except the teeth, tips of scapes, funicuU, 
tarsi and articulations of legs light brown or yellowish. 

Porto Rico: Santurce (Wheeler). 

Though at once recognizable as an Attiine ant, this species is neverthe- 



1907.] Wheeler, Fungus-growing Ants of North America. 729 

less so unlike any of the species of which I had seen specimens or descrip- 
tions that I at first decided to make it the type of a new genus or subgenus. 
Professor Forel, to whom I sent specimens, has kindly given me a worker 
of a species which he took some years ago in Colombia. This species, 
which he will describe as M. emeryi, is intermediate in certain characters, 
such as the structure of the frontal lobes, between the above described 
hritkmi and M. squamosa F. Smith (= uncinata Mayr). M. emeryi differs 
from britioni in having a much longer and more slender thorax, pedicel, 
legs and antennse, in being of a lighter (brown) color and in having the ap- 
pressed hairs on the body and legs, long and not scale-like. The clypeus, 
lower surfaces of the mandibles and the gula have conspicuously long and 
projecting hairs. The petiole is nearly twice as long as broad, the postpetiole 
slightly longer than broad and with a deep rounded excision in the middle 
of its posterior border. The mandibles are more slender, with' more oblique 
blades and fewer teeth. The epinotal teeth are distinctly longer and directed 
upward. The frontal carinse are snialler and the tips of the antennal scapes 
extend further beyond the posterior corners of the head. According to 
Mayr's description the thorax in the worker of squamosa is furnished with 
teeth and projections like the more typical Attii. The Porto Rican and 
Colombian forms therefore approach Apterostigma and Sericomyrmex 
much more closely than do the other known species of Myrmicocrypta and 
may be regarded as the simplest and most generalized members of the genus, 
if not of the whole Attiine tribe. I take great pleasure in dedicating the 
Porto Rican species to the distinguished botanist. Professor N. L. Britton, 
with whom I passed rnany delightful and profitable hours collecting plants 
and insects in Culebra and Porto Rico. 



Part III. Ethological Observations. 

1. Atta texana Buckley. 

In the United States this large "cutting" or "parasol" ant (Fig. 7, 
and PI. XLIX, Figs. 11-14), is the only species of the tribe Attii that forms 
sufficiently populous colonies to be of any economic importance, or, indeed, 
to be sufficiently common and conspicuous to attract the attention of any 
one but a myrmecologist. Although unable to determine its exact range, I 
have found no indications of its occurrence outside of a rather restricted area 
in Texas. This area appears to have its center at Austin and to comprise 
the territory for some hundreds of miles north and south in a narrow belt 



r.so 



Bidhtiii Aiiicriciiii Miiscinii <// Nulurid llislnri/. [\'<il. XXIII, 



wherejtherc is a iiioilcnitc annual rain-l'all and wlin-c llic forests are of a 
mesophytie charaeter. 1 liave never seen it in the dry western portions of 
the state nor have 1 heard of its occurrence in tiie more luiniid eastern coun- 
ties, in I^)iiisiana or tiie otiier (iulf States. It was seen as far south as 
AHce in Xueoes County, and ])rol)ahly occurs as far nortii as Waco and 
Fort Worth. It certainly could not endure the winters of the " Panhandle " 
region nor even those of the extreme northeastern poriion of Texas. Even 
in the vicinity of Austin lar^'e colonies of Attn tc.nuKi are rather sporadic. 
It ]irefers the neifjlihorhood of rivers and creeks and especially the rich soil 
of the pecan and the jiure sand or somewhat clayey soil of the ]i()st-(iak 



^^ 




Fig. 7. AUii texanii Buckley; nialf, ili'illiitfil ffniiiii', siililiiT and MTii-> of wurkcrs; iiiiUiial 
si«'. (.PhotogrHpli l).v Mfs.sis. 0. T. Jirue.s ami A. L. Mcliuiclcr. i 



woods. In such spots one is always sure of lindiufi; it alonji; the hanks of 
the Colorado, Comal and (uuKlelonpe Hivei-s. 

The nests are nearly always silualecl in |)laces fully exposed to the sun, 
in clearings of the woods, in fields, along roads, etc. In some localities, 
as at Elgin, 1 have found them in the sand-hallast of the railway tracks. 
The nests can be recognized even at a distance as very Hat inoimds usually 
not more than one to two dcm. high, with very uneven surface and con- 
sisting of sand or soil of a lighter color than the surface of the surrounding 
country. Closer inspection shows that tliese mounds, which may cover an 
area of nianv square meters, li.-ive Ix'eii derixcd from the walls of craters. 



1007 



Wheeler, FuiKjus-groiriiig .\>its oj Xarlli Aiiirricd. 



■washed down and fused widi one iinotliei- l)y the rains. Se\-ei-a I perfect 
and recently constructed craters are eoimnonly found on the toji or about 
the edges of the mound, and in the case of Jar^fcand active colonies these may 
be numerous, as in the nest shown in l''iif. S, which was situated on the left 
bank of the Colorado River between Austin and Montopolis. The craters 
in this instance covered an area of more than 100 s(|. in. although the ne,st 
had not been in existence long enough to form a distinct niouiid. They 
varied from a dcm. to half a ni. in diameter and From a fi'w cm. to a dcm. 











ri*.\*; 







Fig. 8. Large AUa tcxiuiu iicsi uu ilu- li-fi hunk ul ilu- I'.i 
and Moiitopolis, Texas. (Pliotograpli by Mr. C. G. Hiirliiuiiin.i 



high. Their typical form is shown ii] l''ig. 0, which is taken from the nest 
represented in the preceding figure. The wall of the crater is often higher 
on one side than on the others, or it may be crescentic, that is, interru])ted 
at one part of the circumference. 'J'he (ijx'iiing at the bottom \arics from 
3-6 cm. in diameter, is often xcry ii-i-cgular in outline and leads \crti<'ally or 
somewhat obliquely downward into a gallery of thi' same diameter. The 
large size of the opening is evidently an adaptation for two very different 
purposes, first, for enabling flu' ants to <'arry in their pieces of lea\-es more 



r32 



BiillcUn American Museum of Xaliind IJistiinj. [Vol. XXIII, 



easily, ami second, for ventilating the subterranean portions of the nest. 
In the nests of Attn tcxana I have been unable to detect two kinds of craters, 
one used as entrances, the other for ejecting the exhausted portions of the 
fungus gardens, as Forel has observed in the Colombian AUa ccphalotrs 
and as I have observed at f'uernavaca, Mexico, in the nests of .1. mexicana. 
All the craters when fresh, consist of large, uniform pellets of earth or sand, 
3-5 mm. in diameter, which are carefully compacted and carried to the sur- 
face by the workers. The grains of sand or earth .seem to be held together 
merely by the moisture that permeates the soil at the depth from which they 
are dug, rather than by any snlivary .secretion such as von Ihering supposes 



"S-rt 




•f*^ .13 







: W4 

- 3 :.-\ V-l 



Fig. 9. One of the craters of the AUa texanu nest represented in the preceding figure, about 
i natural size. (Pliotograph liy -Mr. C. G. Hartmanu.) 



the Brazilian A. .scxdfii.s to employ for this pin-|)ose. Tiie pellets disinte- 
grate in the first rain, so that the walls of the craters become lower and more 
rounded and fu.se with one another to form the low mound of older nests. 
The ants usually work at only a few of the craters at a time, and as only one 
or two of the openings arc used when the ants are busily engaged carrying 
in leaves, it seems jjrobable thtit the greater number of craters is con- 
structed for the aeration of the nest and not for entriince or exit. 

The depth and extent of the excavations vary, of course, with the size 
of the colonv, its age, and the character of the soil. This is evident from the 
following notes on three ne.sts examined at different .seasons of the year. 



1907.] Wheeler, Fungus-groioing Ants of North America. 733 

April 10, 1900, Messrs, A. L. Melander and C. T. Brues assisted me in 
excavating a moderately large nest situated at the base of a juniper on the 
banks of Waller Creek, at Austin. There were at least twenty craters on 
the summit of the flat mound, which was about 5 m. across. These entrances 
measuring 2.5-4 cm. in diameter, were found to lead downward as tubular 
galleries converging towards and uniting with one another more and more, 
till a depth of about a meter was reached. Here each of the galleries, now 
greatly reduced in number, entered the top of a large chamber with vaulted 
roof and level floor. Some of these chambers were fully 30 cm. in diameter 
and 25 cm. high and as broad as long, others were much elongated. They 
were sometimes connected with one another by means of broad galleries, 
especially when lying at different levels. The rootlets of the juniper ran 
through some of the chambers or hung down freely into their cavities. Each 
chamber had a large placenta-like gray or white fungus garden covering 
the greater portion of its floor. Small gardens of a more nodular form also 
hung suspended, enveloping the juniper roots, which seemed to have been 
left untouched by the ants, during their excavations, for this very purpose. 
Each garden was a comb-like or sponge-like mass of triturated leaves and 
juniper berries, permeated and covered with a mould-like mycelium. This 
mass . exhaled a rather pleasant odor not unlike that of stale honey, and 
crumbled so readily under the touch that it was impossible to remove it 
entire. It swarmed with workers, the soldiers being least, the mimims most 
numerous, whereas the medise were intermediate in numbers as well as in 
size. In one of the gardens we found the aged mother queen of the colony, 
three winged males, and a number of larvaj. Several of the disintegrated 
gardens together with many of the ants were carried to the laboratory and 
placed in large glass jars. By the following morning the insects had com- 
pletely rebuilt their gardens. The coarser work of carrying and building 
up the particles of leaf-pulp fell to the lot of the mediae, while the minims 
went about planting and pruning the tiifts of fungus hyphfe. The huge 
soldiers merely stalked about on the surface of the gardens, often breaking 
down under their weight the walls of the delicate comb. The ants were 
confined in the jars for several days, and after the expiration of a week I 
made an observation that did not impress me as important at the time: 
the gardens, which were iri a much less flourishing condition than when first 
installed in the jars, were seen to be covered with droplets of a brown liquid. 
As these droplets closely resembled those since described by J. Huber 
{vide ante, p. 698) as the excrement of the female Atta sexdens, it is probable 
that the soldiers and mediae, unable to add fresh leaves to their rapidly 
deteriorating gardens, resorted to the very same method of manuring the 
mycelium as that employed .by the queen^4i!te while she is founding her 
colony. 



734 



Bulletin Ainiriain M iisciu/i of Xalunil 11 isturij. [\'()1. XXIII, 



November 3, I'JOO, I excavated a larjic nest of Alfa tr.rinia situated on 
the left bank of the Colorado Elver al)oiit a mile Avest of .\iistiii. This 
nest was in pure sand at the edge of a sorghum field about lo in. above the 
river bottom where it was overgrown v.itli low willow, prcau and 'lexas 
persimmon trees. The ants were busy di foliating the willows and carrying 
their leafy burdens up the bank and into the nest along a path about 80 m. 
long. At intervals along this |)atli pil.'s of leaf-clip])ings, dro])ped by the 
ants, lay drying in the sun. 'I'lie leaves were cut by th,' mediie in the manner 
described by Moeller for the South .\mericaii .\('ri)iiii/niii\r iliscit/mt. The 




Fig. 10. Hiirlon Si)rini,'s. nrar .Xiistiii, 'IV-Niis. the classic locality for the study of Atta 
tc.f<iii(i. (PhotoKi-ajili Ijy .Mcssfs. Briies ami .Mchmdcr. I 



nest was in a promontory aeeessil)le from three sides, one of which formed 
the wall of a small ravine. The craters were very numerous and nearly 
all on the summit of the bank. The arrangement of the galleries and 
chambers was very similar to that described for the nest on Waller Creek, 
except that the chambers were at a lower level (1.5 to 2.3 m.) below the sur- 
face and iiiiich larger. One of them, of a ereseentic form, measured nearly 
1 m. in length and 30 cm. broad and high. All of the chambers, of which 
I examined fully a dozen, were situated in a (lain])er layer of sand than 



1907 



'heeler, Fiiii(jiis-(/riiiriiii/ Anl-t of Xurlli Ainiriea. 



735 



that ovcrlviiii; tliciii ami <cinlaiiic(l liiijjc riini;'n,s-uarilciis on (licir flaltcncd 
floors. These gardens were 10-15 cm. hiirli, of a yellowisli (•()h)r hclow 
and made up very largely of triturated sorghum leaves. Above they weri' 
l)luish or greenish gray and tiiis v>as the only portion that v.as permeated 
and covered with the living inycehiim, tiie lower |)orlions having lost their 
fungus-Tioiirishing stihstances. The large amount of this exhausted leaf- 
|)ul|) still retained in tlie ehanilK'rs, shov.cd that Alia le.niini must difl'er 
from some of the tr()|)ieal species of tliis geiuis, v.hiili carry il to the surface 




Fin. 11. I.urire Alln iixaiui iii'st on ihf liKlu l>;iiik of Hiuiii 
(Photograi)Ii liy Me^.srs. limes aiui .MelainU'r. ,> 



ck Ileal' Ausliii, Tfxa.s 



and eject it from the craters. Tlie Texan species siin|)ly keeps on liuilding 
uj) its gardens till they reach a considerahle thickness while the mycelium 
retreats to the more nutritive superficial layer. Many of the gardens in 
the nest under discussion contained work.T larva' and pupie in alinndance, 
hut no .sexual forms, either mature or iinuiatnre. liolh in this and in the 
[ireviously described ne.st I found many specimens of a lillle myrmecophilous 
cockroach, of which F shall have more to say in the sequel. .Mllinngh the 



736 



lUdlctin Amcricdii Mii.srinii cij Xahirtil lliKtorij. [Vol. XXIII, 



nest was easily excavated, owinji; lo its localinii in an exposed hank oF ])ure 
sand, nevertheless ] was made verv uneonirorfaMe b_v the jittaeks of the 
soldiers, who actually drew Ijloofl with their sharp mandibles. 

An interesting nest was ex("nated and measured by ^lessrs, Brues and 
INIelander during the spring of 190.3. This was situated on the right bank 
of Barton Creek (Fig. 10) near Austin, about 1 ') m. above the bed of the 
stream. In surface view (Fig. 11) it pr<'sente(l a low, irr>'gular mound, con- 



Oo^-n-^L 




Fig. \2. Uiasjnuii of :lie Atla lexana nest reprcsemcd in iho prucLcling figure. (From a 
slipfch by Messrs. Brues and Melander.) 



sisting of fused or contiguous craters of jiure sand resting on a layer of blue 
clay. As shown in the- diagram. Fig. 12, galleries descended vertically from 
these craters through the blue clay layer, which was nearly 2 m. thick, and 
continued down through an equally thick layer of red c'lay, where they 
entered a layer of pure sand about a meter in thickness. At the top of this 
last layer they opened into a munberof large chambers c-omnnmicating with 



1007. 



Whrder, Fiuujus-ijrou'hiij Ants of North America. 



■3: 



one another hy means of short fiullerics. Tlie cliMnilK'r.s occupied tlie entire 
layer, so that the total depth of the nest was very nearly 5 ni. Some of tlie 
chambers broken open by the ])ick, are represented in Fii;. 18. In the 
lowermost of these one of the large fungus gardens is .seen in .sitn resting 
on the floor. From the lower series of chambers a number of galleries 
continued down through another layer of clay, and finally united to form a 
single long gallery, which ran at first horizontally and parallel with the 
.stream, but finally ro.se obliiiuelv and oijened on the surface of the 1 1,111k 




Fig. 13. Exposed cliambers of iie.st repri-st-iUfd in tlie two pieoediiig figures A large 
fungus garden is shown in situ in tlie lovverniost cliaiuber. (Pliotograpli bv Messrs. Brues and 
Melander.) 



a few meters above the water level and at a distance of fully 05 ni. from 
the nest! This remarkable tunnel was the entrance through which the 
long file of workers brought the leaf-clippings to the chambers. The crater 
openings on the to]) of the l)ank .seemed to be u.sed only for excavating and 
ventilating purposes. That some of these, however, were the original 
entrances of the nest was proved by the pre.sence of small dilatations or 
chambers only a few em, in diameter in the course of the vertical "'alleries, 
[Sept., 1907.] 47 



738 Bulletin American Museum o] Natural History. [Vol. XXIII, 

These dilatations, two of which are indicated in the diagram, must have 
represented the chambers of the incipient nest and one of them was undoubt- 
edly the original cell excavated by the mother queen of the colony. 

In collecting the vegetable substances to serve as a substratum on which 
to grow their fungus, the workers of Atia texana seem to show no evidences 
of discrimination, further than that a colony usually concentrates its atten- 
tion on one kind of material on each of its forays. I have seen workers of 
the same colony at different times cutting and carrying home the leaves 
of plants belonging to the most diverse natural orders. They seem indeed 
to prefer plants with small or rather narrow leaves, but the texture of the 
leaves is apparently a matter of little importance, for the ants may be seen 
defoliating soft herbs like the sheep sorrel (Rumex acetosella) or the clover, 
and anon attacking the tough leathery foliage of the live oak {Quercus 
virginiana). But even hard berries like those of the juniper are collected 
and embedded entire in the gardens. Once I saw a colony carrying away 
the cracked grains of maize from a hominy mill, and on another occasion 
the same colony was assiduously gathering large caterpillar droppings that 
had rained down from a plane tree near the nest. These ants occasion- 
ally enter gardens and defoliate rose-bushes or other ornamental shrubs 
or destroy tender vegetables, but their inability to concenti-ate their attacks 
for several consecutive days on particular species of plants, and the some- 
what smaller size of their colonies than those of the tropical ^Ww, make 
them much less dangerous economically than might be supjjosed. 

Like many other Texan ants, Atta texana is more sensitive to the heat 
than to the sunlight. I infer this from the fact that during the winter and 
cool autumn and spring months it forages at all times of the day but during- 
the hot summer months carries on its excavations and goes abroad only 
during the cool night hours. The sensitiveness of these ants to heat and tO' 
the humidity of the air is also shown by the fact that they carefully close 
their nest craters with earth, leaves, or sticks during hot, dry spells. This 
seems to be an adaptation for preventing the escape of the moisture from the 
nest through the large ventilating galleries and the consequent injury to the 
proliferating mycelia in the gardens. While opening the nest chambers 
of this and other species of Attii I have often seen the delicate fungi wither 
up within a few moments after exposure to the dry air. 

I have not observed in Atta texana the method of comminuting the leaf- 
clippings but there can be little doubt that it is very much like that em- 
ployed by A. cephalotes and Acromyrmex discigera as described by Tanner 
and Moeller. The macroscopic structure of the gardens (Figs. 14 and 15) has 
been correctly, described by McCook {ante, p. 679). Their microscopic 
structure resembles very closely that of the Acromyrmex studied by Moeller. 



1907. J 



Whcdcr, Fungus-growimj Anln oj North America. 



739 



There is the same beautiful, wliitc myirhimi with hy|)ha' .(l-.S a in diauu'tiT 
everywhere threading and coverinf; the eonih-hke leaf-|)ulp and densely 
dotted with ehisters .2-. 3 nun. in (hauieter of the small spherical or jx-ar- 
shaped food-hodie.s (Kohlrabikopfclien) ,'3-.").,") /z in diameter. As Ma'ller's 
terms for the.se structures are rather far-fetched, since to English-speakinir 
peoples at least the kohlrabi is by no means a familiar vegetable, and as the 
structures really deserve somewhat more dignified or at any rate more tech- 




Fig. 14. Entire fuiigu-s garden of AtUi tcxiutti, abont 1 nalnral size. 
Messrs. Brnes and .Melander.) 



(rii(itograi)li by 



nieal ap])ellations, 1 would suggest that the globular swellings of the hypluc 
be called gangylidia and the grape-like clusters whieii they form, hromatia. 
The arrangement of the leaf-i)ulp at the surface of the gardens in the form 
of thin walls or plates greatly extends the expo.sed surface of tlie substratimi, 
favors the growth of the plant, and thus increases the amount of it that ean 
be raised in a circumscribed cavity. This arrangement also facilitates the 
control of the fungus and its cultivation and makes it more accessible as 
food. 



740 



Bulletin American Museum of Xalunil Ilistuni. [\"iil. XXIII, 



Some well-developed iiieans of iiUercoiiiiminication would seem to be 
necessary for ants like Attn tr.ranti which live in jjreat colonics and co(>|)ei'ate 
so intimately both on their forajiinj; e.\])editi()ns and in the cultivation of 
their delicate food plant. 1 am convinced lliat ihis means is supplied by the 
stridulatory organs which are highly developed in all the castes of the species. 
As I have shown in a former paper,' the .stridnlation of the huge females of 
Atta texana is audible when the in.sect is held a foot or more from the ear. 
The male and soldier to be audible must be held somewhat closer, the largest 
workers still clo.scr, whereas the smaller workers and mimins, though stridn- 
lating, as may be seen by the rapiil movements of the gaster on the post- 
petiole, are quite inaudible to the human (-ar. It is |irobablc that all these 







Fig. 15. Portion of fiiiiRus garden of Alia texana tniilt up l)y ants in conllnciniMit. (Plioto- 
grapli ijy Messrs. Brnes and Melander.) 



differences in the rate of vibrations, or humanly sjx'tiking, of jiitch, corre- 
lated as it is with a differentitition in the size and functions of the vtirious 
castes, is a very imjiortant factor in the coi)|)eriition of these insects, espe- 
cially in the often widely sepanited subterranctm cavities in which they 
spend so much of ihcir livi's. Miss Ficldc and Prof. Parker'- htivc recently 
given good reasons for conclnding that thesi- vibrtitions are tninsmitted 
through the .soil or other solitls and not through the air, and that they are 
therefore perceived by the ants through iheir legs as tactile iiiih<'r than as 



1 Ethological Observations on an American .\iit ( Leptotliorax Eraersoni Wheeler). Arch, 
f. Psycliol. u. Nenrol., II, 1903. p. 19. foot-note. 

2 Tlie Reactions of Ants to Material Viljration.s. Proc. .\cad. Nat. Sci. Pliila., Sept. 1904, 
pp. 64:^-630. 



1907.] Wheeler, Fungus-growing Ants of North America. 741 

auditory sensations. Ttiis result agrees also with, the accounts of others 
who have investigated the perception of vibrations in insects. 

Of all ants the Attii would seem, at first thought, to offer in the great 
sponge-like masses of decomposing vegetable matter of their fungus gardens 
the most favorable of resorts for all kinds of myrmecophiles and synoeketes. 
But the number of such animals hitherto observed in the nests of these 
ants is very small. This is probably due to the exquisite care and diligence 
with which the ants patrol and cultivate all parts of their gardens to 
prevent the growth of the aerial hyphse, alien fungi and bacteria, for under 
such circumstances any intruder might be easily detected and ruthlessly 
destroyed. Nevertheless a few animals have managed to secure a foothold 
in the nests, but so far as known, only in those belonging to species of Attci 
s. str. and Acromyrmex. I have never seen any traces of myrmecophiles 
in the many nests of Trachymyrmex, Mycetosorites and Cyphomyrmex which 
I have examined. Bates (1892) and Brent (1886) state that certain Amphis- 
bsenian lizards manage to live in the Atta nests of Brazil and Trinidad. It 
is probable that these reptiles feed on the ants. Belt (1874) mentions a 
large Staphylinid beetle as occurring on the Atta nests of Nicaragua, and 
Wasmann (1900) concludes that this beetle, which he identifies as Smilax 
pilosa Fabr., is probably a true myrmecophile, because it so closely resembles 
the large Atta workers in its dark brown color and abundant pile. The 
same author (1894, 1895) mentions several Histerid beetles (Philister 
rufulus Lewis, Hister ( ?) costatns Mars, Reninus salvini Lewis and Car- 
cifiops (?) multistriata Lewis) as having been taken from the nests of Atta 
mexicana, and three Staphylinidse belonging to the genera Aleochara and 
Atheta from the nests of A. sexdens. These are probably all not true 
guests but synoeketes. To the same group belong also a number of speci- 
mens of the myriopod Scutigera which I found running about in the galleries 
of an 4. texana nest. 

The only myrmecophiles known to live in intimate relations with Attiine 
ants are the small and aberrant cockroaches of the genus Attaphila of which 
I described the first species (A. Jungicola, PI. LIII, Figs. 47-49) from Texas 
(1900). This insect, which is very common in the fungus gardens of A. 
texana, measures only 3-3.5 mm. in length. It is yellowish brown and has 
very small eyes, one-jointed cerci, and peculiar antennae, consisting of a few 
cylindrical joints. The females are wingless, the males have vestigial teg- 
mina and hind wings. The antennte are always imperfect, their terminal 
joints having been bitten off, in all probability, while the ants are clipping 
the fungus mycelium. The structure of the remaining antennal joints is so 
unlike that of all other Blattidte that Attaphila must be regarded as the type 
of a distinct subfamily, the Attaphilince. Since publishing my description of 



742 



Biilldiii Amrrirmi Miisatm <ij Nnlunil llisldry. [\'ol. XXIII, 



this singular insect, I have luid an (i|i|ii)rtuinl y (if (ihsrrviiii; it in artificial 
nests. It does not feed on the fungus liy])hR' as I at first su|)]iose(i, hut 
mounts the backs of the largt- soldiers while they are stalking about the 
garden and licks their surfaces after tile manner of some of tiie myrme- 
co])hiles of other ants, notably the little cricket }I iiriiircnphiJ(t tirJirasccn.ns, 
the Staphylinid beetle O.ri/.tonia oliniliiirri. an<l I he guest an( I.cptofliin-a.r 
cmersoni. 

In 1901 Boli\ar described a second s])ecies of AlUtphilii (A. Iinr/i), which 




AriZ' 



Fig. 16. Nest craters of Alfa (^f^rll(rius) versicolor l*eii.'iiiHle in a tsaiuly "draw" at Yucca, 
izona. (Pliolograpli by the author. J 



was discovered many years tigo by Herg in tlie nests of Arromjirmex liindi 
in Argentina and Uruguay. 'I'liis s])ecies (PI. LlII, Figs. 50-54) is very sim- 
ilar to the Texan form and it too, seems always to have multilated aiUcnna-. 
According to Berg "it is found in the nest of the ants, sitting on the back, 
neck or even on tiie head of the sexual individuals (never on the neuters), and 
when these swarm forth during the spring or siinnner, it is also carried out 
of the nests, still attached id its host." 



1907.] 



Wheeler, Fungu><-(inne}ng Anta of North Ainerica. 



743 



Atta (Moellerius) versicolor I'l^rf/diidc. 



This ant is unqiiestionablv a Mexican sp- 



SIX'CR'S WlllCll ( 



■liters the United 
States only along its southwestern frontier where it iniiahits the arroyo 
bottoms in the most arid regions. I have observed the typical lorni of the 
species only in two localities, at Tucson, Arizona, and at '^'ucca in the same 
state, a few miles east of the Californian boundary. At Tucson several 
colonies were found in an arroyo near the Carnegie Desert Hotiinical La bora- 




Fig 17 One of the craters of tlie group represeim-d in the preceding figure, al)out i 
natural size, sliowing tlie difference between tlie pellets brouglit up by the auls and the surround- 
ing soil. (Pliotograpli by the author.) 



tory where the soil was probably somewhat moist at a depth of several feet, 
but where the surface was very hard and dry and covered witii typical de.sert 
])lants such as the retania {Parkinsonia), the siikiH acacia known as "cat- 
rlaw" or "ui'ia de gato" (Ararin (/rrc/r/i), the Mexican grease-wood (('(rvilln'a 
t ride II lata), the ocotillo (Foiiijiiicrn .splriKlciis) and several cacti {Opnntki). 
At Yucca the ants occur in similar arroyos bordered witli tiic bcatitirul ])od- 
willows (Chilop.il.s xulirjiia) in tiic midst of a very hut, dry desert, stuilded 



744 



Bulletin American Museum tif Xnliinil Nistori/. [Xo]. XXIII, 



with clumps of canatilla {Ephedra), hiijre tnr-lib' yuccas, :iii(l ■'allthorn" 
bushes (Kosberlinia). In botli localities the nests were surmounted hy from 
one to a dozen craters, varyinj; from 10- .SO cm. in diameter, and of verv 
elegant and regular structure (Fif;s, Kiaiid 17). This was noticeably the case 
at Yucca, where the craters were built of the coarse, uniform .sand of the 
arro\T) bed. The earth or sand of the crater walls was often of a diH'erent 
color from the sun'oniidiu^- sui-Fmcc, sliowino- iIkiI il li.id lie;'n brought u]) 




























,r. )i7*''- !*<■,, ^in-il' ci-atiT 111 Attn 'Muiltniif! r,r>:injlnr cuvt-rcl with leave.-, (if Kiva.se wood 
llovUlwa) collecteu by the ants at Tmson. .\rizoiia. These leaves are also scattered along 
the path leading to tlieerater (iiiiper right hand corner of tiKiirei. i I'lioIoKraph hy the author.) 

from il considerable depth. The opening at the bottom of the crater was 
2-3 cm. in diameter and was often closed with etirth. Even about the open 
craters no ants were to be seen during the intense hciil of the day. JJetween 
four and five o'clock in the afternoon, however, they were seen leaving the 
nests in files, and slowly moving towards some desert shrub in the neighbor- 
hood for the purpo.se of cutting ;ind cttrryiiig home its leaves. At Tucson 
some of the colotiies were collecting the endi-e \c)iin<r and tender leaves of the 



1907.1 



Wheeler, Fungus-ijrowinij Anls of A^orth Aiiirrica. 



745 



"cat-claw," and had c-oiiiplftt'ly dcl'iilialiMl sdiiic of the hushes (Figs. IS and 
19). Other colonics were carrying in tlu' small Icalhcrv leaves and yellow 
flowers of the grea.se-wood. ("onsiderahle (|iianti(ics of these leaves had often 
been gathered and dropped along ihc path or on the craters, as shown in Fig. 
18, and left to wither in the siui when the aiits withdi-cw into their nests dur- 
ing the night or early morning hours. 

The colonies were much smaller I haii those of .1 1 In I r. ran a, althoujrh ihev 




Fig. 19. Acacia Ijusli dcrolialfd by AlUi (Mallcriiis) fcrniivlar at Tucson, Arizona. U'lioto- 
grapli liy tlie aiulior.) 



comprised several hundred workers. 'Hicsc varied considcraldy in size, 
especially at Yucca. Dr. William Camion, din'dor of thi' Desert Labora- 
tory, kindly a.ssi.sted me in excavating one of the nests which had only a single 
crater. The entrance gallery, about 12 cm. in dianicier bi-okc up into a 
number of small anastomosing galleries just beneath the surface and these 
reunited to form a single g.-dlcry extending down into coarse, friable saiul to 
a depth of about a meter and terminating in a single small chamber which 
contained a ftuunis cfarck'ii about the size of a walmit. This i>ardcn was 



746 Bulletin American Museum of Natural History. [\^ol. XXIII, 

lying on the floor of the chamber and consisted of fine leaf-pulp covered with 
a brilliant white ■mycelium dotted with bromatia. No other chambers or 
galleries could be found, and as the nest contained only about one hundred 
workers, the colony must have been incipient or enfeebled by age or adverse 
conditions. As we had spent a great deal of time excavating this nest, and 
,as the heat was intense, so intense, in fact, that it caused the gutta-percha 
plate-holders of my photographing outfit to soften and crumple, we could 
not command sufficient energy to excavate a larger and more typical nest. 
Unfortunately my stay of only a few hours at Yucca did not suffice for the- 
exploration of one of the much finer nests of that locality. Judging from 
the single nest examined at Tucson, Mwllerius versicolor resembles most 
■of the species of Acromyrmex described by Moeller, Tanner, von Ihering 
and Forel in having only a single chamber and garden. 

My notes on the- subsp. chisosensis are even more fragmentary.. At 
Terlingua, Texas, in the Great Bend of the Rio Grande, I found a few dead 
workers of thisform in a spider's web under a stone, but was quite unable 
to locate the nest from which they came. ' Judge O. W. Williams, however, 
brought me a number of fresh specimens from a nest in a dry arroyo at the 
foot of the Chisos Mountains some miles southeast of Terlingua. Both 
localities are in very arid deserts, riven with canons, though the vegetation 
is of a different type from that of southern Arizona. The red quicksilver- 
bearing soil supports a sparse growth of the sotol {Dasylirion texanum), 
'desert spurges (Euphorbia antisyphilitica and latropha spathulata) and 
lechugilla (Agave lechugilla), and the steep canon walls are spangled with 
star-like resurrection plants (Selaginella lepidophylla) and xerophytic ferns. 
Such a region, with an annual rainfall of barely 25 cm., is certainly a remark- 
able environment for an ant compelled to subsist on fungi that can grow 
only in a humid atmosphere, an ant, moreover, belonging to a group which 
was probably first developed iii the rain-forests, of the tropics. 

3. Atta (Trachymyrmex) septentrionalis McCook. 

The species of Trachymyrmex form small colonies of at most two or 
three hundred, and often of only a few dozen individuals, and are so timid 
and retiring in their habits that they are readily overlooked unless their 
nests happen to be numerous and close together. And even when numerous 
the nests are not often seen as their earth-works disintegrate and their en- 
trances are kept closed during considerable periods of the year. 

Our best known species, T. septentrionalis, is widely distributed over the 

Gulf and South Atlantic States, the var. ohscurior ranging from central 

Texas to Florida and the typical form from Maryland to New Jersey. There 

--are"^ no observations to show that either of these forms extends equally far 



1907.] ■ Wheeler, Fungus-growing Ants of North America. 747 

north in the Mississippi Valley. Mr. Wm. T. Davis has found the typical 
form as far north as the Raritan River in New Jersey and although he has 
hitherto failed'to take it on Staten Island, it may yet be found in certain parts 
of Long Island. Both forms of the .species have the same habits, although 
the southern variety often makes larger and more complicated nests and ' 
lives in larger colonics than the typical northern form, which is always more 
or less depauperate, like all ants at the limit of their geographical range. The 
following description, except in so far as it relates to the size and complexity 
of the nest, will apply to both forms of the species. 

According to my observations, T. septentrioiialis , even in widely separated 
localities, always occupies a very precise ethological station. ■ I have never 
fouhd it except in pure sand and in open woods. , It is abundant in the post - 
oak woods of Texas, especially in the neighborhood of Milano and' Monto- 
polis,, wherever the red clay is replaced by sand, in the hummocks of Florida 
(Miami, Jacksonville) and the pine barrens of New. Jersey (Lakehurst, 
Toms River, etc.). The. plant associations in all of these localities have a 
common facies in tliat they always comprise several species of oaks and 
many other plants and animals peculiar to the Louisianiari portion of the 
Austroriparian subprovihce. 

Externally the nest of T. septentrionalis is very unlike that of any other 
North American ant known to me. It consists of a little mound of sand 
varying from 10 to 20 cm. in diameter, and a few cm. in height, of an ellip- 
tical, round, or crescentic form and placed at a distance of 5 to 10 cm. from 
the entrance. The latter is circular and varies from 4 mm. to 1 cm. in 
diameter, and the gallery into which it leads invariably slopes so as to form 
an angle with the surface. The sandpile lies in front of the entrance. The 
external appearance of one of these nests is shown in Fig. 20, from a photo- 
graph taken at Lakehurst, where the sand is often covered with the needles, 
twigs and cones of Pinus rigida and inops. The subterranean portion of 
the nest consists of from one to three series of straight galleries alternating 
with more or less spherical chambers, so that it is possible to distinguish a 
simple and a racemose type. To the former belong the young nests of the 
var. ohscurior and all the nests of the typical septentrionalis, whereas the 
racemose type seems ito occur only in old and flourishing colonies of the south- 
ern variety. 

In the table on page 749 are given the dimensions in cm. of the galler- 
ies and chambers of ten nests of T. septentrionalis var. obscurior examined 
in three localities about Austin, Texas, nests A to F being of the simple, 
and G to J of the racemose type. Diagrammatic sections of nests C, D, ,F, 
and G-J, drawn to scale, are represented in Pis. LI to LIII, Figs. 37-42, 45. 
The entrance gallery is called gallery I, that between chambers I and II, 
gallery II and so on. Of the two measurements recorded for each chamber, 



748 



Bulletin Aimricdii Mit.-<('iii/i <ij Xdliiml IHsldnj. [\n\. XXIII, 



till' first is the ilcjith or vertical, the S('c< md the lircaillli or transverse ilia meter. 
The chambers are either spherieal, or if one diameter exceeds the other, it 
is most frequently the transverse, so that the chambers are often oblately 
spheroidal. As the galleries enter and leave the chambers at opposite 
points on their roofs and floors, the glol)iilar cavities have the appearance 
of being stnmg on the galleries like beads on a string. The most frequent 
nests are those of the form A-(", comprising only I wo galleries and two 
chambers, and these are the only ones described by pievious observers 
(Morris, McCook, Swingle, Forel). Tlie entrance gallery is commonly a 




Fig. 20. Nest of Atla (Trdchiimyrmex) septentriandUs in jiine biuieii iipar Lakehurst, New 
Jersey, about i natural size. Tlie circular entrance is in the iniiUlle of tlie tiRiire: the excavated 
sand is dumped out in a heap in front of it (liclow). (I'liotograph liy the author ) 



few cm. in length and tlic fii-sl clianiber is vei-y snuill (2.S X ,3.2 cm. on an 
average). These represent the whole of the nest dug by the mother (jiicen 
while establishing her colony, the other chambers and galleries being added 
subsetinenlly by the workers. The (able ;ind I lie lignres show verv clearly 
that the length of Gal. II and the size of Ch. II, greatly exceed the qneen's 
excavations and are in turn surjjiissed by subsetincnt exctivations (dais. 
III-IV and ("lis. III-\'). Xcsts with tliree, four and live clitimbers, like 
I), E, anil F, are rarely encotnitered. Of the last I have seen only a single 
example and this was peculiar in having C'hs. Ill and IV deeper than broad. 



1907.] 



Wheeler, Fungus-growing Ants of North America. 



749 



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750 Bulletin American Museum of Natural History. [Vol. XXIIJ, 

Nest D was unique in having Chs. II and III opening directly into each; 
other. Nests of the simpler racemose type, like G, arc more frequent than 
simple nests with as many as four and five chambers, like D and E. In 
nests G-I the second gallery sent off a branch terminating in a chamber of 
its own (Ch. Ila). The terminal chamber of nest H (Ch. Ill), like that of 
nest E (Ch. IV), was Yerj small and obviously in process of being excavated 
by the ants. In nest I the insects had completed at least a portion of the 
gallery (Gal. Ilia) leading from Ch. II and the ants, had they been left 
undisturbed, would probably have widened its end into another chamber 
(Ch. Ilia). In nest J, the largest and most complicated of the series, not 
only did Gal. II form two branches, but one of these divided in turn, so 
that there were three galleries, each terminating in two chambers (Chs. II a, 
b, c, and Ch. Ill a, b, c) separated by a gallery (Gals. Ill a, b, c). Since 
in all of the nests the galleries formed an angle with the surface of the sand, 
their total depth, as given in the last column of the table, does not represent 
the vertical distance of the floor of the terminal chamber from the surface, 
but the oblique distance from the entrance. Both simple and racemose 
nests, moreover, though represented in the figures as lying in a single plane, 
are often bent, or, like nest I, of the latter type, radiate out from the entrance 
in three different intersecting planes. 

TVhen establishing their formicaries the ants select only those spots in 
the woods where the sand is permeated with fine rootlets. They are careful 
to leave these untouched, while hollowing out their chambers, as supports 
for their gardens, which in this, as in other species of Trachymyrmex, are 
always pendent and do not rest on the floor of the chamber like the gardens- 
of Atta s. str., Acromyrmcx and MwUerius. The substratum on which the 
fungus is grown consists very largely of caterpillar excrement and withered 
oak-catkins, both picked up under the trees, but often small dead leaves or 
berries are used, and occasionally as Morris and McCook observed, flowers 
or green leaves are cut from the small herbaceous plants in the neighborhood. 
These substances are comminuted and placed on the pendent rootlets where 
they become knitted together by the rapidly proliferating fungus mycelium. 
The whole garden then hangs from the roof of the chamber as a cluster of 
nodular strands or plates separated from the walls and from one another by 
spaces sufficiently large to admit the ants to all parts of the structure. The 
first chamber, in which the original worker brood was reared by the queen, 
is often empty or has lying on its floor particles of exhausted vegetable sub- 
stances ready to be carried out of the nest, or materials that have just been 
brought in. This chamber seems to be the work-shop in which the materials 
are prepared for insertion into the hanging gardens of the lower chambers. 
The appearance and arrangement of several of these gardens are shown in 



1907.] 



Wheeler, Fiiiiiiii.f-i/rdii'iiiii Aiiln oj Nortli Anicricn. 



75 r 



Pis. LI— LIII, Figs. 30 — IG. Tlie inyccliiiin in lldiirisliiriij; cDloiiics lias a 
bluish tint, .somewhat like that (if I'rnicUlhuit (/lanciiiii. Tiu" hy])luu measure 
.78 fi in diameter. The gongylidia are suhsjdierieal or jiear-shaped, and 
average 4.5 it in length and 3.(1 n in iircadlii, and are gi-dupci! in cdinpaet 
clusters or bromatia averaging .4-. 5 nun. in diameter. 

In Texas the most favorable time to study the nests of T. tibxciiriar i.s 
during the month of April. '^I'lieu I lie ants are actively enlarging and deejien- 
ing their nests and bringing in su|)|)hes for their gardens. While excavating 
they advance in a small phalanx u|) tlie inclined entrance gallery, each laden 
with a cuboidal sand pellet about 2 nun. in dianieler, walk slowlv to the 
sand [)ile, de])osit their burdens and then return for others. The dc:ilate<l 
females, of whicli tlu're may be as many as four or five in a nest, toil in the 




Fi^. 21. Brood of AWi yTrttchiiniiiniux) <ih.^curi'n\ -Xhoiii iwici- naiiiral size. Ttxree 
packets of eggs are shown enveloped in fungus mycelium. (Pliolograpli Ijy Mr. A. BeutemnUUer.) 



phalanx like the workers. .\t the sliglitesl alarm the ants ininu'dialely 
retreat into the nest and usually a single worker takes up liei' position in the 
entrance and holding a sand-pellet in her jaws, waits ])atiently till all danger 
has passed, before venturing forth and leading the troop of her sand-laden 
sisters. When foraging the ants go out singly and in various din'ctioiis, 
pick up what they can find and return with it to the nest, moving slowly 
and sedately over the sand. 'Hie dealated females may also lie .seen in the 
act of carrying cater])illar droppings and leaves to the nest. If rudi'ly 
touched with the finger or a stick, the in.sect drops her burden, curls herself 
up, folds her legs and antennpe and "feigns death." .\t such times her 
rough yellowish brown body is almost indistinguishable from the sand on 
which she lies. When the nest is ruthlessly torn open, the ants, es|)ecially 



752 



Bulletin Aiiiiriraii Miisniw nj Ndliiral llistiiri/. \\'t>\. XXIII, 



if they Miv ininicnius anil liavc a lari;e brood, do not fci^n dcalli l)nt boldly 
assail the intnuk'r with their nian(lil)l<'s. 

Tlie nests remain in fine condition tlirou;:'liout .May and the earl\' ])art 
of June, while the youn;;' are bciii;;- i-eari'd. The eggs are broadK' elli])tical 
and eniljedded in masses in jmre white hyjdue. (Fig. 21.) The.se delicate 
vegetable strands .serve to keep the eggs together, thus enabling tlie ants to 
carry them about in packets, afford an admirable |irol((tion and, as soon 
as the larva- hatch, re])resent a su])))ly of very accessible food. The older 
larvre and young pu])a>, however, are always free from adhering hypha', so 
that their surfaces arc smooth and glistening, till they (levclo|) the rough, 
tubereulate integument of the adidt staye. Tlic bi-ddd is undoubtediv 














Fig. 22. Nest of Alta (Trachymyrmcx) septcnirionalis var. obsniruir in siiiidy post-oak 
wood near Delvalle, Texas. About J natiinil size. Tliis represents the conrtliion of tile nest 
during the dry summer. A few .sticks and dead leaves cover the eniranee just below tlie middle 
of the figure. (Photograph by Mr. C. G. Hartniann.) 



moved from chamber to cliainber In suit the varying conditions of heat tind 
moi.sture. Throiigliout the wiirm dtiys of May and June it is kept in the 
superficial a])artmcnts. < )n the morning of June 1 1 , li)03, after an unusually 
cool night, I found the ants and entire brood of .several ne.sts huddled together 
in the lowermost chambers, but during the warm afternoon of the stime dav 
the young had been brought very near the suri'ace. .\t Miami, Florida, 
the males and females were nuiture and ready for the miplial flight as early 
as ^Nlay 9; in Texas I have not seen them in this condition till the .second 
week in June, and to judge from tlie date on the label of ti winged female 
in my collection the .sexual jiha.ses of the typical form iId not mature in New 
Jersey till some time in ;\iigust. 



1907.] Wheeler, Fungus-growing Ants of North America. 753 

When its nest is disturbed, T. septentrionalis, like other Attii is very 
careful to rescue portions of its fungus gardens as well as its brood. A 
number of colonies, whose nests I had excavated in the post-oak woods at 
Montopolis, were found a few days later to have made new nests a few feet 
from the old sites and to have carried with them such fragments of their 
gardens as they could rescue. They had suspended these to the rootlets in 
one or two chambers which they had succeeded in excavating in the mean- 
time, and were busy carrying in caterpillar excrement and withered oak 
catkins. 

During the spring and autumn T. septentrionalis may be found abroad 
at all hours of the day, but with the growing heat of the summer it becomes 
increasingly crepuscular and nocturnal. And as soon as the dry weather 
sets in, it greatly contracts or completely closes with dead leaves and twigs 
the orifice of its nest to reduce or prevent the evaporation of the moisture 
from the chambers. The sandpile subsides under the influence of the ele- 
ments till the nest becomes barely distinguishable from the surrounding 
leaf -strewn surface (Fig. 22). It is then almost impossible to find the 
nests even in localities where previous exploration has shown them to be 
very numerous. The stnts no longer venture forth but spend all their time 
weeding and rearranging their gardens in the moist subterranean chambers. 
Immediately after the first warm rain, however, the nests are reopened, ex- 
cavations and repairs to the chambers are renewed, the exhausted portions 
of the gardens are ejected and the ants sally forth in quest of fresh supplies. 

4. Atta (Trachymyrmex) turrifex Wheeler. 

As this species is even more timid and retiring than T. septentrionalis, 
it was some time before I learned to find its colonies and gained an acquaint- 
ance with its habits. Its geographical range covers the dry deserts of Trans 
Pecos Texas, and slightly overlaps the range of septentrionalis along the 
escarpment of the Edwards Plateau in the central portion of the state. 
That it is a more adaptable ant than its eastern and northern congener, is 
shown by its occurrence in the following diverse stations : 

1. In the treeless deserts at Del Rio, Langtry, .Marfa, Alpine and Ft. 
Stockton, in dry stony soil fully exposed to the glare of the sun. In these 
localities the colonies are widely scattered. 

2. In the clayey soil of the post-oak woods and "cedar-brakes" (Juni- ■ 
-perus sahinoides) near Austin (Fig. 23), along the Perdenales River, and at 
Marble -Falls. Here the colonies are often numerous and close together. 

3. In the pure sand of open fields at Montopolis on the Colorado River. 
In this locality the colonies are infrequent and mingled with those of sep- 

Sept., 1907.] - 4S 



754 



Hiilliiiii Aiiuriciin Mii.i(iiiii aj Xntuidl II islarii. [X'ol. XXIII, 






:tm^^ 



~^ v ■ 'SI'' ■ ■^' w Ai ■ 'i ' 




Kig, 23. "Cedar Brake" (Jtiiiiiiinix siilniinidr.if near Aiisiin, Texas. Home of Attn (Truchu- 
myrtnex) turrifcx. (Phutograplj b.v I'rul. \V. J.. I!ray.; 



1907 



Whcclcr, Finujun-iirowiiiif Anl-s of North Anifn'ca. 



i iiO 



tfiifriiimilis^ a condition which also ohiains in sanily porlioiis ol' l he ))osl-oak 
woods. 

'rhouj;;h structurally closely reseinliliiiij' the eastern species, T. inrrijcx 
may be readily distinguished l>y a inimher of etholo^ical charac'ters. Its 
colonies are much smaller, often consisting of only two or three dozen individ- 
uals. Xevertheless a single nest may contain as many as four or five deiilated 
females. The nesting hahits are most conveniently studied in the post-oak 
wooils, where the ants prefer to live in the shade of the trees. Here the 
red clay is overlaid with a stratum of less compact black soil two or three 
decimeters deep. The external structure of the n^'st is very dilVerent from 




Fig. 24. Turret -.sliapt'd futriinci.' to I'.t'st of Mtii i Tnichnmr/rtnci) turrifcx iu u ucdui- br;iku 
near Austin, Texas. ^Pllutograpll by Mr. .\. L. Melamlcr. ) 

that of ■tcptriiirioiKilis. The orifice is only -'5 t inni. in diameter and in 
ty])ical ne.sts, does not open on the surface of the soil but at the to]) of a 
cylindrical turret or chimney about 10 mm. in diameter and from 10-41) mm. 
high. The walls of this turret, which arc mad.- of earth particles, small 
juniper twigs and other vegetable debris (Fig. Ii4) are suflicicutly resistant 
to withstand heavy showers. As the nests are often located on sloping 
ground the turret would seem to be an ingenious adaptation for keeping 
the water from entering the subterranean galleries ami chambers. Occa- 



756 



Bulletin American Museum of Natural History. [Vol. XXIII, 



sionally I have found nests with abnormal turrets, like the one represented 
in PI. L, Fig. 27, which has the summit enlarged and spreading and pro- 
vided with three distinct orifices. . The pellets of earth bnjught up by the 
ants are cuboidal or polyhedral, of uniform size and measure about 2 mm. 
in diameter. They are not cast to one side as in septentrionalis but in a 
closed circle at a distance of 8—12 cm. from the entrance. As this circle 
grows in height it forms a very shallow crater with the turret rising abruptly 
in its center. In the post-oak woods and cedar-brakes the eastings are red 
or dull vermilion and contrast strongly with the black soil or dead leaves 
of the surface. 

The galleries and chambers alternate with one another as in the simple 
type of septentrionalis nests, but the chambers are smaller and the galleries 
are much longerand usually descend vertically into the soil. .These differ- 
ences are distinctly shown in the figures (PI. LI, Figs. 33-36) and in the 
measurements (in cm.) of the accompanying, table. 

Atta (Trachymyrmex) turrifex Wheeler. 









^^ 


hH 


- 


- 


> 

h4 


> 


> 


> 




























CJ 






a 














x: 


°S. 


a 


o 


o. 


o 


o 


o 


o 


o 


o 


o 


o 


HQ 



K 

L 
M 
N 

P 


3.7 
1.8 
2.5 
3.6 
3.6 
3.8 
• 3.5 
10.2 


1.8X1.8 
1.3X1.3 

.8X1. 
1.3X1.8 
1.3X1.3 
2.5X2.6 
2.6X2.5 
2. X2. 


4.2 
8.2 

11.6 
6.5 
2.5 
1.6 
6. 

23. 


1.8X2,6 
2.8X2.8 
3.2X3.2 
3.6X3.8 
2.5X5. 
2.5X3.8 
4. X4. 
6. X6.4 


5. 

9.5 
14.6 
11.6 
12.8 

6.3 
18. 
19. 

12. 


3.8X3.8 
.4X6.6 
4.2X6.4 
3.8X7.6 
5, X6,4 
4. X5.2 
2, X2,5 
2,6X3.8 


6.3 

13.4 

15.3 

7.5 

7.5 

■ 9. 

16.5 

30.6 


4. X4,2 
3,2X6,5 

5, X5, 
1.5X1.5 
5.2X7.5 
4. X6.5 
3.5X5. 
6.5X7.8 


7.7 
17.4 

10.5 
15. 

8. 


4.5X3.8 

6.5X7.8 
3.8X3.8 


38.3 
66.1 
57,1 
39,2 
40,4 
50,6 
70, 
110,5 


Ave. 


4.1 


1.7X1.7 


7.8 


3.8X3.9 


3.6X6.2 


13,2 


4,1X5.5 


11.7 


4.9X5.1 


69,0 



All of these nests were located in the clayey soil of the post-oak woods 
except the last (R) which was in pure sand. Owing to the length of its 
galleries, this is exceptional in its total depth (110.5 cm.), and therefore 
abnormally increases the average length of the galleries I to V in the table. 
The average depth of nests K to Q is only 50.8 cm. which is less than half 
the depth of nest R. ■ The nests usually comprise four chambers (Fig. 25), 
but five are often met with, and here, as in septentrionalis, the galleries and 
chambers have their dimensions suddenly increased, below the first chamber, 
which is the work of the mother queen. I have seen but one turrifex nest 
that resembled the racemose type of septentrionalis in having two branches 
to Gal. IV, each terminating in a chamber. Comparing the nests of the two 
species we see that both start v\'ith the simple, primitive type consisting of 



1907 



Yhiilir, Fiinijus-gwiring Aiils of Xorlli A iiKrini. 



757 



altcriiatinij pilleries ami iliaiiii)ci's and that tiirrijrx I'onliiiiics its excava- 
tions according to this jjattem, whereas flt)iirishing colonies of firptnifrioiia/is 
change to the racemose type whicii Ix'ars an nninistakal)le resenihlance to 
the nests of Aita s. str. 

The greater length of tiie fiirnfiw galleries in ])iire sanil is iiiidoiiljtedh' 



■««»' 






'."Till ''":'•' iJ't - l^"^.! *■- , ,.>.-■ V- 




Fig. 25. Section of nest of Alta (Tnicliymi/rnicr) turrip'X .sliowiiii; four elmniliers exposcil 
at poinl.s of jiaper triangles numbered 1 to 4j. .Al)Out i natural size. (Photograph by Mr. 
!;. Ci. Hai'tnuuiri.) 



due to the need of reaching a stratum of greater dampness. In the drvTrans 
Pecos deserts tlie same tendency i.s ob.servahle. In that region I re])eatedly 
endeavored to excavate nests, but was never ahlc to i-cadi ilic cliaiiiijers on 
account of the extreme hardness of the stonv soil. I am conviiicrd, liov,- 



758 Bulletin American Museum of Natural History. [Vol. XXIII, 

ever, that these nests were more than a meter deep.' That T".- turrifex 
reqviires rather moist soil is also shov\'n by a peculiarity of its nests in the 
post-oak regions. Here, as I have said, the subsoil is )'ed clay overlaid Vidth 
a dryer, and more porous black earth. The ants not only carry their ex- 
cavations dovvn into the subsoil but carefully line the galleries and chambers 
in the black soil, to the very orifice of the turret, with a thiii layer of clay 
brought lip from belovi-. Thus the nest becomes a bottle with thin clay walls, 
alternately constricted into slender tubes (the galleries) and dilated into 
ampulliform enlargements (the chambers). This clay lining is probably 
a very efficient means of preventing both the escape of the moisture from the 
chambers during dry spells and the entrance during rainy weather of too 
much moisture from the soil. Unlike the nests of septentrioiialis; those of 
turrifex are not closed during the dry season. Such closure is in fact un- 
necessary because the nests are considerably deeper, situated in soil which 
retains the moisture much longer, and have very small orifices. 

The first chamber, like that of the seftentrionalis nest, is used as a work- 
shop and temporary repositor}' for fresh and discarded vegetable substances. 
The rootlets of plants are also left dangling into the remaining chambers 
as a suspensorium for the fungus gardens. These resemble the gardens of 
seftentrionalis but are smaller, whiter, and of a more delicate texture, as if 
the vegetable substratum on which they were grown had been more finely 
comminuted. In the confection of this substratum the same materials are 
used, viz., the withered catkins of oalcs, the scales of buds, bits of dead leaves 
and the excrement of caterpillars. I have never seen these ants cutting or 
bringing in green leaves of any description. At Marfa and Ft. Stockton 
they were collecting the withered florets of a small yellow composite {Pedis 
tenella). The nest openings were often surrounded by a circlet of these 
florets, so that to one riding over the desert each nest seemed to be marked 
by a small handful of saffron. All of the vegetable substances are picked 
up by the ants from the ground and not collected directly from the plants, 
as turrifex is even less inclined than sepfentrio7ialis to climb about on the 
vegetation. The microscopic structure of the fungus gardens is very much 
like that of sefUnirionalis. The hyphse measure .78 n in diameter; the 
bromatia .3-.4 mm. and consist of beautifully developed gohgylidia 3.5-4.7 /i 
in length and somewhat less in breadth. 

The dealated females of ttirrifex take part in excavating and foraging, 
like the workers. On one occasion, early in the morning of June 14, in the 
midst of the desert at Marfa, I came upon a whole colony of this ant, com- 
prising some thirty workers and five dealated females, in the act of digging 
a- nest in the hard adobe soil. They had evidently been corhpellcd to for- 
sake their old nest during the night on account of the drought, which was 



1907.] Wheeler, Fungus-growing Ants of North America. 759 

almost unprecedented even in that region, as it had not rained for nine 
months. As I have also found many abandoned nests of this ant in the 
cedar brakes about Austin, I infer that it not infrequently migrates to more 
favorable spots. It would be interesting to know v^'hethe^ on such occa- 
sions the old queens carry over to the new quarters portions of the fungus 
gardens in their hypopharyngeal pocket, or whether the workers transfer 
the old gardens piece-meal during the cool night hours. The latter would 
seem to be the more probable procedure. 

T. turrijex is, if anj'thing, slower and more sedate in its movements 
than septentrionaUs. It also "feigns death" more readily and never seems 
to resent the destruction of its nest. Only a few workers are seen at any 
one time outside the nest. The slightest disturbance causes these to with- 
draw into the turret, and one may sit motionless near the nest for many 
minutes before they muster sufficient courage to venture forth again. When 
several of these ants, together with pieces of their gardens, were placed in a 
dish with a number of se-ptentrionalis workers, a conflict ensued, in which 
the latter were the aggressors and came off victorious. They carried the 
turrijex garden piece by piece into a wide chamber they had excavated in 
some sand at the bottom of the dish, but by the following morning they had 
thrown it all out again and, although they had been without food for several 
days, they would have nothing to do with it. 

The breeding season of turrijex must come later in the summer than 
that of septentrionaUs. During early June I found a few young larvse in 
the nests of the former species, but the only winged female I have seen was 
captured in flight by Mr. W. H. Long on September 27. I have never been 
able to obtain a male of this species. 

5. Atta (Trachymyrmex) jamaicensis Em. Aiidre. 

Like the preceding two species of Trachymyrmex, T. jamaicensis, though 
confined to the West Indies, occurs only in association with a xerophjtic 
flora. It is a larger, much darker ant, with unusually long legs and antenna;. 
I found it first in the Bahamas, on both Andros and New Providence Islands, 
On the former it was seen wherever I landed and searched for it — at Big 
Wood Key, Mangrove Key, on several of the uncharted keys along the 
course of the Southern Bight and about Crawl Creek. On New Providence 
it was found in the neighborhood of Fort Charlotte. It prefers to nest in 
the pure white foraminiferous sand of the sea-beach, at or just above high 
water mark, along the edges of the 'coppets' which consist very largely of 
■coarse grasses, sea-grape, cocoa-plum, wild sapodilla, sea-lavender and 
jjalmettos. Its nest, which is most readily found by tracking foraging 



760 Bulletin American Museum 'of Natural History. [Vol. XXIIT, 

workers, is surmounted by a very flat and obscure crater about 30 cm. in 
diameter with an oblique and somewhat eccentric orifice 5-10 mm. in 
diameter. The ants collect buds, small flowers, bits of dead and living 
leaves and caterpillar excrement as a substratum for their fungus gardens. 
When rudely touched the workers fall over and "feign death." At first I 
was inclined to believe that this species is restricted to the sandy seabeaches, 
but on walking inland about two miles from All Saint's Rectory at Man- 
grove Key, I found it nesting also in clearings among the 'coppets' wherever 
a small amount of rich black soil in the cavities of the rough ^Eolian limestone 
had induced the negroes to plant maize and other vegetables. Here the 
ants were busily engaged in cutting and carrying into their nests bits of the 
green maize leaves after the manner of the species of Atta s. str. In other 
places, like Fort Charlotte, on New Providence Island, the ants were nesting 
in the dry shady 'coppets.' In all of these localities the nests extended 
down through holes or crevices in the limestone, so that I was unable to 
obtain a satisfactory conception of their structure. 

On a recent trip to the Island of Culebra, a few miles east of Porto Rico, 
I again encountered this ant but under conditions more favorable for study. 
The vegetation on Culebra, which is too low to intercept the rain-laden 
trade winds from the Atlantic, is decidedly xerophytic. There is no stand- 
ing water on the island and the short arroyos dry up very soon after a shower. 
A number of colonies of T. jamaicensis .were found in the shade of the trees 
on the banks of thesearroyos. The colonies, at the time of my visit (March 
2-9), were in an opulent condition and each comprised numerous larvae, 
pupse and winged niales and females in addition to about a hundred workers. 
Externally the nests, though in black friable soil, were like those on the sandy 
beaches of the Bahamas. Their subterranean structure closely resembled 
that of the simplest, two-chambered nests of septentrionalis . The entrance 
descended into the soil obliquely and at a distance of 2-3 cm. below the 
surface, widened into a small spherical chamber 2.5 cm. in diameter. This 
chamber contained no fungus garden but only a few workers apparently 
engaged in comminuting leaf clippings and caterpillar excrement. A second 
gallery 5—10 cm. in length led ofi^ obliquely from the bottom of this chamber 
and terminated in a larger spheroidal cavity 6.5-9 cm. in diameter, filled 
with a flourishing fungus garden of coarse and nodular structure and sus- 
pended from rootlets. The brood, callow and recently matured sexual 
forms were ensconced among the pendent folds and strands. The mycelium 
was of a bluish color, like that of septentrionalis, with hyphse .58 [j. in diameter. 
The bromatia measured .36 mm. and consisted of well-developed pyriform 
gongylidia 4-4.6 ,« long and 1.5-3 fx broad. 



1!)()7 



Whrrlrr, Fuiii/u.t-i/rouiiii/ Ants of Xoiih Annriin. 



■61 



6. Atta (Mycetosoritis) hartmanni sp, ika. 

This interesting little ant was discovered May II, l'J()3, in the sandy 
country on the left bank of the Colorado Uiver at ^Nlontopolis and Delvalle, 
near Anstin, Texas, while, with the assistance of .Mr. ('. (J. I lailiii.'inii, I 
was exaniininiT and ])liotoi;ra))hini; the nests of Traclii/iiii/niir.r iiirnfc.v 
and srplcntrionnlix. At first I was inclined to regard the diniinntive workers 
as merely heloiigiiig to iii<'i|)ient 'rmi-hi/iiii/niir.r colonics, hut closer sttidy 
soon showed that tln'se little ants were not oidy s])ecifically distiiK t hut also 
represented a new and interestini; stihgeiuis. in certain res])e( ts intermediate 
between Trarln/iiii/niic.r and ('i/phoiiiifnNc.r. There were hundreds of 
their nests, often within a few decimeters of one another, in the fields or in 
clearings among the oaks and wherever the sand was fully exposed to the 
sun. These regions were also iidial)itcd b\- se\cral species of solit.iry wasps 










'■^> 




Fig. 26. C'lMtiT of Atta > M ijiyj'if"nlix} Iciiiiiuiinn Ircmi s;iihI,v po^i-calv woods iit Monto- 
polis, Texas. Natural size. (.Pliotograpli Ijy -Mr. C. G. Hariiiuiiiii.) 



(M irrobriiilii'.v i\Ui\ I'oiii i)ihi.^) and nuini'fotis colonics of ants ( 'rrdcln/iiii/niic.r 
tum'fc.r and .frptnifriniin/is, A phirmii/iis/ir ln<itii\ I'liintnlr .ip/iiiilidiila and 
tnorrini, Sofniop.iix t/riiiiniilii, l'ii(/<iiiiiiiii/nnr.i- rdiiiiniclir, rrfiii}lrpi.s arriiir(if/fi, 
etc.). The herbaceous flora of the region cotisistcti of a spar.se growth of 
bull-nettles {latwplia Ktliinihtsa), showy gaillardia ((Idillin-dia pulrhflhi), 
butterfly weed (A.iclfpia.i liihrru.ia), white prickly ])oppy {Arr/cminic a/lxi), 
stone crop (Scdinn) an<l cactus {Opiintlfi ciKjrhnaiiiii), all in ftill bloom. 

The nests of the Mijrrfosorifis are small lurrirorm cratcfs of pure sand 
5-8 cm. in diameter at tiie base and tapcritig rapidly to the sunnnit, w hich 
is 2. .5-4 cm. high ant! perforated with a circular firifice barely 2 mm. in 
diameter (Fig. 26). Occasionally the stimmit is doiililc (PI. ly. Fig. 28) 
and ftirtiishcd with two entrances, which, howc\cr, soon utiite to form a 



rr.2 



Blilh'tiii American Miiminii tij Ndlnral JI i'-inrij. [^'(ll. XXIII, 



single gallerv. The intcrii;il strucdirc ol' tlic nest reseinblt's on a small 
scale that of Truflii/nii/niir.i- liirrifr.r. It consists of from two to four alter- 
nating vertical galleries and s])heroi(lal chamhers. As the former are very 
tenuous and run through pui'e sand, (he excavation of lh(- nests is rather 




Fit:. 27. Section of iie.st of .4/^^ ( .U,//r^^^^■^;■///.s■^ Imrtwinni in jmrf- >:iimI al iJc-lvulle, Te.xa.s. 
About J natural .size. (Photograph 1>.\" Mr. C. (.!. Hanniaiin.j 



difficult. The measiu'cnienls of six of these nests (S to X) are given in the 
accompanying table, ditigrams of three of them tire re])rcsente(l in Figs. 
30-32, PI. U, and photographs of portions of one of tlicin in Figs. 27 iind 
2S. 



1007.] Wlicrlrr, FuiH/iis-giyiiriiii/ Ants of Xarth Aincrica. 

Al(a iMi)C(l<ii«iriti k) iKirtiiiaitui f-p. iiov. 



763 



Gill. lial. (;al. Tct:.! 

Nest I Ch. I Gill. 11 fli, 11 111 Cli. Ill IV L'h. IV Depth 



s. 


5. 


2. X2.5 


15. 


2.6X4. 


_ 




_ 




24.6 


T. 


6.3 


1.3X2. 


20.5 


2.5X4. 


1.8.5 


2.5X3.4 


— 




51.6 


U. 


5. 


1.4X1.4 


13. 


2.5X4. 


20.4 


2.5X4.5 


— 




53.4 


V. 


7.6 


1.3X1.3 


13.3 


3.3X3.8 


7. 


4. X4. 


— 




36.5 


w. 


6. 


1.2X1.3 


18.7 


2.3X3.7 


20 


2.0X4.1 


14 


2.X3.4 


67.1 


X. 


5.2 


.8X1.5 


28. 


1. X3.2 


25.3 


2.5X4.5 


14 


2.x 3.4 


78.8 


Ave. 


6.5 


1.3X1.6 


18.1 


2.3X3.8 


19.8 


2.8X4.1 


14 


2.X3.4 


52.1 



'J'lic galleries arc j)r(i|iiirtii)nally longer than those of liirrijcx nest.s in 
clay or black soil, and the ciianihers are ahsolntely .smaller ami more oMatclv 




Fig. 28. One of the pendent funsn.. sarilen.s of the nesl shown hi the preceduig figure, 
sli.irhtly enlarged. (Phologiiiph b.v .Mr. C. G. Hartnninn.j 

spheroidal. On an average, however, the Mi/(rti>fiorili.t iiests are quite as 
deep (55.1 cm). 'I'heir resemblance to tiirrifc.v nests in pure sand, like nest 



7()4 



HiiUctin Anirricrin Museum of Ndtiinil Hi.'<t(iri/. [\ii]. XXIII, 



R of tlie talilc "11 |). 75('), is gri'atcr (iwin;; In llic clonj^alidii ol' (lie if:illci'ii',s 
of the latter sjiet'ie.s. 

Like the species of rrdfhi/iiii/niii.r, M. luiiiiiiiniin leaves the rootlets 
dangling into the chambers as siispcnsoria for its fungus-gardens (Fig. 28). 
These gardens, however, have a nnicli more delicate and floeculent texture 
and are made up almost exclusively of the anthers of plants, knit together 
l)V a snow-white mycelium consisting of slender hyplue ..IS /( in diameter. 
The hromatia, wiiicli measure .3-. 4 mm. consist of typical pyriform gongy- 
lidia l.,!>-4.3 /( in length and 1.3-4 n in hreadth. 

The colonies are small, not exceeding (iO In 70 workers. ( )nly a .single 
derdateci female was found in each of the nesls. 1 was unal)le to find any 



IPi'lH 


1 


^^^^^^^^P^^^ '^^^^^^^^^^^1 


^^^H 


HK^ 


*-*t!!^| 


B^'^^f^Sflit^^^K ' '^^nd^ElP^' "' 


:'f 


H|^^>^^^BBHPh|^^|S9HH|8[$^^'.. . ' 


% 


f^^^^tf '■ ,^ , 





Fig. 29. FuiiKi.- .- 



,11 of Attn ( Mijnta 



and placed on tile ground. iPhotoKrapii li.v .Mr. C. G. Ilail iimiimi.) 



iM'd from the ne.st intact 



JarviP or pupa'. Mr. .\. M. l'"crguson, who liclp>'d nic excavate a nuinher of 
the ne.st.s on one occasion, and kept the ants v>ith .some of their gardens in an 
artificial nest, succeeded later in the summer in rearing the males and winged 
females described on pp. 715-71(1. 'Hie workers are extremely timid and 
"feign death" with the utmo.st readiness. Their small rough bodies arc 
then quite indistinguishable from the sand grains iimong which they lie. 
Only a few workers forage or excavate at a time. They .seek the withered 
anthers where they have fallen or have been drifted by the wind on the sur- 
face of the sand and slowly and laboriously transjiort them to their ne.sts. 
These anthers, manv of which still contain polli'ii givdns, arc inserted entire 
in the gardens and tire evidently rcspoii^ililc for the light and Hoccidcnt 



1907.] Wheeler, Fungus-growing Ants of North America. 765 

texture. Exposure of only a few moments to the air causes the delicate 
mycelium to wither and contract. The garden of the chamber represented 
in Fig. 28 was thus dried, but the one in Fig. 29 was photographed imme- 
diately after its removal from the nest. The ants appear to be crepuscular 
or nocturnal. I have not seen them at work after ten o'clock in the morning 
except on very cloudy days. 

On June 5, when I paid a second visit to the sandy country at Monto- 
polis and Delvalle, all the nests were closed and the craters revealed no signs 
of recent excavation. They had merely crumbled, marking the sites of the 
nests as obscure little piles of sand. I opened several of the nests and found 
the workers moving diligently about in their gardens, which were in fine 
condition. On June 26, when, just before leaving Texas, I paid a final 
visit to the dry post-oak woods, not a trace of the nests could be found. 
The wind and rain had completely obliterated the fragile turrets and fused 
their sandgrains with the surrounding surface, so that even the closest 
observer would never have suspected the existence of innumerable colonies 
of little ants diligently cultivating their hanging gardens in the dark bosom 
of the yellow sands. 

The foregoing description of the nests of Mycetosoritis shows that this 
ant is closely related to Trachymyrmex. The members of the genus Cypho- 
myrmex, as will be seen from the following accounts of two species have 
very different habits. 

7. Cyphomyrmex wheeleri Forel. 

This species appears to be more widely distributed than most of the 
preceding, since it ranges from Central Texas to California and probably 
also over a large portion of northern Mexico. In Texas it is rather rare 
and, according to my observations, occurs only in arid regions, especially 
on the Edwards Plateau and Grand Prairie and in the stony deserts of the 
Trans Pecos country about Langtry and Fort Davis. Although several 
of the preceding Attii prefer to live in dry localities among plant associations 
of a more or less xeropli}'tic habitus, the abode of C. ivheeleri is characterized 
by even greater aridity. Most of my observations on the habits of this ant 
were made among the lime-stone hills of the plateau escarpment just west 
of Austin. Some of these hills, which are often beautifully stratified and 
terraced and belong to lower cretaceous formations, are shown in Fig. 30, 
from a photograph taken in the early morning when the long shadows 
accentuate their peculiar structure. The terraced slopes are strewn with 
blocks of limestone of different sizes. Among these hills, from early spring 
.to late autumn, the heat and the glare of the sun reflected from the white 



766 



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1907.] Wheeler, Fungus-growing Ants of North America. 767 

rock are exceedingly oppressive. Water is very scarce and the vegetation 
is so sparse and stunted or of such a xerophytic character as to yield little 
shade except in the deeper canons. The trees and shrubs comprise such 
species as the mountain cedar (Junipcrus sabmoides), several hackberries 
iCeltislielleri, reticulata and pallida,) oaks (Qtiercus jtisiformis hreviloha and 
sclineckii), buckeyes (Ungnadia speciosa and Msculus odandra), dwarf 
mulberry (Moms celtidijolia), dwarf walnut (Juglans rupestris), frijolillo, 
or coral bean (Sophbra secundiflora), Texas persimmon (Brayodendron 
texanum), madrona (Arbutus xalapensis var. texana), algerita (Berberis 
trifoliata), Eysenhardtia amorphoides, Leucophyllum texanum, Rhus micro- 
phylla and virens, and Ephedra antisyphilitica. During the spring the bare 
rocks are beautiful with a profusion of smaller plants (Gilia rigidula, Castil- 
leia. Salvia texana, Stillingia angustifoUa, Palafoxia texana, Androstephium 
violaceum, Camassia fraseri, Yucca rupicola and Nolina) 

It is only on the higher and more arid terraces that G. wheeleri manages 
to live and cultivate its fungus gardens, where long after other plants have 
bloomed and deep into the winter the golden heads of Actinella scaposa nod 
on their long stems. The nests are always under large stones covering a 
little lingering moisture in the hard soil, which consists very largely of dis- 
integrated limestone. Each colony comprises only a few dozen workers 
and a single dealated female except during the spring and early summer, 
when one finds also several callow workers, males and females and a variable 
number of eggs, larvfe and pupse. The workers are nocturnal, at least 
during the warm seasons of the year, a peculiarity which is indicated by 
their yellow color. They are very slow in their movements and readily 
"feign death." 

The excavations though extensive for such small ants, are unlike those 
of Atta, Trachymyrmex and Mycetosoritis. A few rough and occasionally 
branching galleries about 1-2 cm. in diameter run along the surface covered 
by the stone, and descend vertically into the ground to a depth of 10-15 cm. 
One of the surface galleries terminates in a small entrance at the edge of the 
stone where its opening may be marked by a small crater. Irregular and 
indistinct dilatations in the galleries represent the chambers of other Attii, 
and in one of these dilatations, which is often fully exposed wdien the stone 
is removed, or may be readily, vmcovered at a depth of a few cm., the single 
fungus garden is found. This rests directly on the ground and is spheroidal 
or ovate, usually about the size of a filbert or pecan nut, more rarely half as 
large as a hen's egg. It consists of a. delicate flocCulent substratum made of 
small vegetable slivers covered with a dense snow white mycelium. The 
slivers average from 1-3 mm. in length and appear to have been torn from 
the stems of herbaceous plants. They undergo no trituration or comminu- 



768 . Bulletin American Museum of Natural History. [Vol. XXIII7 

tion before they are inserted in the garden. The mycehum which binds 
these slivers together bears distinct bromatia .6-.7 mm. in diameter and 
consisting of pear-shaped gongylidia 1.5-3.5 fi in length and .78-1.56 n broad. 
They are less globose than the gongylidia of Atta and Trachymyrmex and 
less club-shaped than those of the South American species of Cypliomyrmex 
represented in Moeller's figures. Sometimes as in these species, however, 
they are not terminal but appear as mere swellings in the course of the hyphse. 
The brood is embedded in the fungus gardens and the eggs and young larvse 
and often also the older larvre and pupae are covered with a delicate film of 
mycelium. 

The ants carry all the exhausted particles of the substratum out of the 
galleries and build them into a flat mass which adheres to the lower surface 
of the stone. More rarely this refuse is dumped outside the entrance of the 
nest at the edge of the stone. As the mass of slivers is sometimes nearly 
as large as a man's hand and therefore greatly exceeds the size of the flour- 
ishing gardens, one is compelled to conclude that the vegetable particles 
contain but little available nutriment for the fungus and have to be con- 
tinually renewed by the workers. Moreover, as these masses of exhausted 
substratum are often found under stones covering completely deserted 
galleries, it is probable that the ants keep moving to new nesting sites. 
This moving must be necessitated by the small' amount of moisture in the 
soil and the rapidity with which it evaporates' even from under large stones. 

In the vicinity of Austin, C. wheeleri is not confined to the limestone 
hills of the Edwards Plateau. On three occasions I found small isolated 
crater nests of this species in the hard pebbly soil of the open woods at a 
lower altitude in the outskirts of the town. The exhausted substratum was 
dumped to one side of the small circular entrance which descended vertically 
into the soil. These nests must have been much deeper than the ones above 
described as I never succeeded in excavating them completely or in finding 
the fungus garden. 

The males and winged females were found in the nests on the Edwards 
Plateau June 26th, and as early as June 8th in the somewhat warmer country 
about Fort Davis. In the latter locality I noticed among the vegetable 
slivers of the exhausted substratum a number of el}'tra, thoraces, etc., of 
small beetles, but vvhether these insects had been collected for food or merely 
formed a part of the substratum, I am unable to say. 

8. Cjrphomyrmex rimosus S-pinola. 

• The stations inhabited by the various subspecies and varieties of this 
widely distributed ant afford a striking contrast with the arid environment 



1907.] Wheeler, Fungus-growing Ants of North America. 769 

of,^C wheeleri and entail a corresponding contrast in habits. All the forms 
of rimosus that have come under my observation live in the shade of trees 
and bushes in rather moist, black soil. These ants are, in fact, restricted 
to such localities on account of the material they, require for constructing 
their gardens and the peculiarities of the fungus which they cultivate. The 
habits of the subspecies minutus which I have had abundant opportunities 
of observing in the Florida Keys, Bahamas, Culebra and Porto Rico, and 
those of the subspecies dentatus which I first found in the lovely barrancas 
about Cuernavaca, Mexico, resemble so closely the habits of the var. comalen- 
sis at New Braunfels, Texas, that I may confine my remarks very largely to 
this form. 

i At New Braunfels a number of beautiful springs, the sources of the Comal 
River, gush forth from the foot of Mission Mountain, one of the limestone 
hills that constitute the Grand Prairie escarpment (Fig. 31) . The volume and 
temperature of these springs is practically constant during the entire year. 
They nourish an exuberant vegetation consisting of ash-trees, live-oaks 
and shittim wood (Bumelia lycioides) and a dense undergrowth of sub- 
tropical shrubs and herbaceous plants too numerous to mention. The 
entomologist who enters this undergrowth must be prepared to endure the 
fiery torments of the "red-bugs" or "coloradillos" (" Leptus" irritans) and 
exercise some care lest he tread on a water moccasin. But, if he be in 
search of ants he will be rewarded by finding a number of interesting sub- 
tropical species, among others three species of Pseudomyrma {pallida, 
brunnea and jlavida), a singular little Strumigenys (S. margaritce Forel) 
hitherto known only from the island of St. Vincent, besides the fungus-grow- 
ing ant with which we are here concerned. 

This ant, owing to the close agreement between its color and the black 
soil over which it moves, is more difiicult to detect than any of the other 
small Attii described in the preceding pages. Single workers wander about 
slowly in the damp shade of the plants in search of the caterpillar excrement 
with which they construct their gardens. As soon as one of the short, cylin- 
drical, ribbed pellets is found, tjie ant seizes it in her jaws, raises it above 
her head like a man shouldering a cask and returns home with accelerated 
pace. The slightest touch causes the ant to drop her load, draw up her legs 
and antennae and "feign death." And he must have exceptionally good 
eye-sight who can distinguish her rough, opaque and inert body from the 
particles of earth among which it falls. 

The colonies of C. comalensis are larger than those of C wheeleri, some- 
times comprising a hundred or more workers and from one to three dealated 
queens. The nests are under rather small flat stones or pieces of wood, 
with the entrance sometimes nearly a cm. in diameter, at the periphery. On 



770 



Bulletin American Mugeum iif Nntuml History. [Vol. XXIII, 




1907.] Wheeler, Fungus-groivmg Ants of North America. 771 

removing the stone or piece of wood the galleries are seen to be very irregular, 
running along the surface as in the nests of C wheeleri and extending dowii 
into the soil to a depth. of 20 to 35 cm. They adapt their course to the many 
small fragments of limestone on or below the surface. The single fungus 
garden, of irregularly flattened or sometimes of elongate and straggling 
form lies in dilated portions of the gallery, usually completely exposed by 
the removal of the stone. In many nests the garden rests on a small stone, 
piece of bark or dead leaf from which the earth has been carefully removed 
by the ants. So different is this garden from that of the other Attii heretor 
fore described that it has been completely overlooked by all previous ob- 
servers. The substratum consists of a mass of caterpillar droppings a few 
cm. in diameter, which have undergone so little manipulation by the ants 
that the individual pellets may be distinctly recognized even to the pecu- 
liar ridges produced by the rectal folds of the caterpillars. 

The fungus grown on this substratum is not a mycelium as in all the 
species above described, but is in the form of a number of isolated whitish 
or yellowish bodies .25-.55 mm. in diameter, of the appearance and consist- 
ency of cheese crumbs and of an irregularly polygonal or pyriform shape 
(PI. L, Fig. 29). Each of these bodies may be said to correspond to a cluster 
of gongylidia and may therefore be called a bromatium. It rests with one 
of its angles or surfaces on the caterpillar excrement, but no rhizoids or 
mycelial threads can be seen at this point entering and ramifying in the 
substratum. The whole garden is kept so moist that when first exposed to 
the air the surface glistens with a film of greenish liquid. As the brorriatia 
rest on this liquid, which evidently represents a thick solution of fecal and 
vegetable substances, they are in a position to absorb nutriment directly. 
It is probable that the habit of placing the excrement on the surface of a small 
stone, bit of wood or dead leaf which happens to be found in the gallery of 
the nest, is for the purpose of retaining this nutrient moisture and pre.- 
venting its absorption by the soil. All of these conditions are such as to 
restrict C. comalensis and the other forms of rimosus to moist, shady localities. 
Such situations are of course, also the only ones in which tropical and sub- 
tropical plants are sufficiently abundant to furnish an unfailing supply of 
caterpillar droppings. 

When the bromatia are crushed and examined in water under a high 
power of the microscope, they are seen tO consist of a dense mass of elliptical 
or subspherical cells measuring .78-2 jx in length and .78-1 (i in breadth. 
Among these there are also cells of other shapes and even smaller sizes- as 
shown in PI. LII, Fig. 4.3. The cytoplasm of all of these cells is colorless 
and finely granular and contains one or more clear vacuoles and a few small 
refractive corpuscles. A nucleus is probably present, but I have been 



772 •Bulletin American Museum of Natural History. [Vol. XXIII, 

unable to find it in my preparations. Tlie cell wall is always very thin and 
transparent. These cells closely resemble those of the common yeast {Sac- 
charomyces) except that they are considerably larger. Like the yeast cells 
they may often be found in the act of budding or dividing. In this manner 
probably arise the minute cehs scattered about among those of much larger 
dimensions. All the cells are held together in the bromatial mass merely 
by cohesion of their surfaces without assuming polyhedral shapes from 
mutual pressure, and there is no perceptible intercellular substance nor 
any trace of an envelope enclosing the mass as a whole. 

Neither the rhycologists with whom I am acquainted nor the botanical 
works to which I have access, have given me any satisfactory information 
concerning the natural alEnities of this singiilar fungus. That it must be 
in a purely vegetative stage of growth will probably be admitted, since there 
is nothing to suggest sporulation in the structure of the bromatia or the cells 
of which they consist. It is also evident that this plant must represent 
an entirely different fungus from any of those described by Moeller. Its 
cultivation on some artificial medium, such as. agar mixed with sterilized 
extract of caterpillar excrement, may be expected to throw light on its affini- 
ties and to show that it belongs to some well known genus or species, but 
this can be undertaken only by a trained mycologist. It will be a long time, 
however, before we are in possession of any information in regard to these 
matters, if botanists continue to manifest as little interest in the fungi cul- 
tivated by ants as has been the case during the past fifteen years. In the 
meantime the singular fungus cultivated by C. comalensis and the other 
forms of rimosus over such an extensive area of the American tropics cer- 
tainly deserves a name, and even at the risk of creating a sjTionym, I propose 
to call- it Tyridiomyces jormicarum gen. et sp.'nov. and to assign it provision- 
ally to the order Exoacese, a group which also includes the well-known yeast 
fungi. 

I have proved that the ants eat the Tyridiomyces, by observing their 
behavior in artificial nests. On several occasions colonies were brought 
from New Braunfels to Austin, where they were kept in Petri dishes for 
periods of from one to four weeks and provided with the excrement of cater- 
pillars (Hyperchiria io) which feed on the leaves of the southern hackberry 
(Celtis mississippiensis) . The captive ants were as careful of the bromatia 
as of their brood. When the garden was disturbed they rearranged the 
pellets of excrement and deftly replaced the scattered and detached fungus 
bodies. Workers, females and males were frequently seen holding these 
bodies between their forelegs and eagerly rasping off portions of them with 
their tongues. Sometimes an ant would consume a whole bromatium, but 
more frequently only a portion was eaten. The irregular polygonal shape 



1907.] Wheeler, Fungus-growing ArUs of North America. 773 

of the bodies is undoubtedly due to this method of feeding. It is equally 
certain that these bodies keep growing in size and regenerating the consumed 
portions by a rapid proliferation of their component cells. Caterpillar 
excrement freshly introduced into the nest was "seeded" by the workers 
either with entire bromatia brought from older portions of the garden or 
with small pieces bitten off from the bromatia and sprinkled over the new 
substratum. In the artificial nests the ants were unable to raise sufficient 
fungi for their consumption, so that in the course of a few weeks they de- 
voured all of the bromatia and eventually died of starvation. As a rule the 
substratum employed by C*. comalensis and the other forms of rimosus, that 
have come under my observation, consists exclusively of caterpillar droppings, 
but in several of the nests of the subspecies minutus in the island of Culebra, 
I also found small pieces of plant substances which I was unable to identify 
and a few small decomposing insect larvje. These were mingled with the 
caterpillar excrement and also dotted with flourishing bromatia. 

On one of my artificial nests of comalensis I made an observation which 
proves that this ant can also eat animal food. Several of the larvfe and pupse 
that had been injured while the colony was being captured were eaten with 
avidity not only by the workers but also by the males and winged females. 
They did not, however, eat other insects, such as flies and small beetles, 
which I placed in their nest. The remains of the larvse and pupee were 
eventually inserted among the caterpillar excrement and carefully seeded 
with pieces of bromatia. This would seem to indicate that the beetle frag- 
ments seen in the nests of C. wheeleri at Fort Davis may have been similarly 
employed as a portion of the substratum. 

Both in the natural and artificial nests of C. comalensis and minutus the 
brood was carefully kept to one side of the damp fungus garden, which 
would certainly be a very unwholesome and inappropriate nursery com- 
pared with the flocculent gardens of other Attii. The larvEe of comalensis 
were fed by the workers with small pieces of the bromatia.' I have seen a 
few virgin females in the nests of this variet)^ as early as May 10, but these 
and the males were not found in numbers till June 10 to 21. In the more 
southern countries, such as Culebra and Porto Rico, the winged phases 
appear as early as March and April. They "feign death" like the workers, 
but the males less readily than the females. 

9. Atta (Mycocepunis) smithi Forel. 

This species, originally described from the island of St. Vincent, seems 
to be widely distributed through the West Indies and Mexico, but I have 
seen it only in Porto Rico, where it is represented by the variety borinquenen- 



774 Bulletin American Museum of Natural History. [Vol. XXIII, 

sis. Owing to its retiring liabits and small size, it is very easily overlooked. 
A few isolated nests were found in the open fields and among the cafetals 
and platanals along the turnpike which, winds through the picturesque 
mountains between Arecibo and Ponce. These nests and one found in the 
curiously eroded, country about Vega Baja between San Ouan and Arecibo, 
were small, obscure craters less than 8 cm. in diameter, made of earth of a 
different color from that of the surrounding surface and therefore brought 
up from some little depth. I made several attemj^ts at excavation but was 
never able to find the fungus gardens. Finally I discovered a nest in moist 
red clay under a stone on the shady slope of Mount Morales near Utuado at 
an altitude of about 400 m. The ants, about 30 in number, had constructed 
a small tubular entrance at the edge of the stone and had excavated a tenuous 
gallery about 5 mm. in diameter for a distance of several cm. along the sur- 
face covered by the stone to a small irregular chamber. In this I found the 
fungus garden which consisted of a mass, hardly more than 2 c. cm. in volume, 
of caterpillar droppings, studded with bromatia which differed from those 
of Cyphomyrmex rimosus only in the somewhat greater volume of their 
component cells (PI. LIII, Fig. 44). This difference is, however, probably 
of little importance, as the material from which the figure was drawn was 
more recently preserved than that represented in PI. LIU, Fig. 43. As C. 
minutus and Mycoce'purus borinqucnensis occur in the same localities it is 
quite possible that both ants may cultivate the same species of fungus. 

These observations though very meagre, are nevertheless sufficient to 
prove that in its habits Mycocepurus is much more closely related to Cypho- 
myrmex than to any of the subgenera of Atta. It would be ]3ermissible 
therefore to regard Mycocepxirus as an independent genus. 

10. Myrmicocrypta brittoni sp. nov. 

My brief glimpse of the Jiabits of this Porto Rican ant would be hardly 
worth recording, were it not that no observations have been published on 
the habits of the remarkable genus Myrmicocrypta. M.. brittoni was seen 
only at Santurce, a suburb of San Juan, while I was accompanying Pro- 
fessor N. L. Britten on a botanical excursion. The ants were nesting in 
the sea-beach just above high-water mai'k and over a narrow strip of the 
adjacent shore in a large grove of cocoanut palms. The black workers 
stood out in strong contrast with the white sand over which they were mov- 
ing in the bright sunlight. The nests, which were very nvmierous and often 
only a few meters apart, resembled those of Trachymyrmex turrifex as' they 
were in the form of flat, circular craters, 8-10 cm. in diameter, very shallow 
in the middle and with the vertical entrance gallery terminating on a small 



1907.] Wheeler, Fungus-growing Ants of North America. 775 

turret about a centimeter high. Under the palms the sand of the craters 
was often of a deep red color, unlike that of the surrounding surface, so that 
the galleries must have been rather deep. Unfortunately my stay in this 
.locality was so brief that I could not examine the nests at my leisure. Al- 
though I subsequently collected in many localities on the island, I never 
again encountered M. hrittoni. Santurce is, however, easily accessible from 
. San Juan, and the future observer will have no difficulty in finding the nests 
and of learning much more concerning the habits of this interesting ant. 



Part IV. The Attii and the Other Fungus-growing Insects. 

Many insects, especially of the orders Coleoptera and Diptera, either in 
the larval or imaginal stages, are known to feed on fungi, but the ability to 
cultivate or to control the growth of these food plants is, so far as known, 
restricted to certain termites, Scolytid beetles and ants. The taxonomic 
relationships of these three groups to one another are so remote that we are 
compelled to regard this control as the result of convergent development. 
In other words, the fungus-growing habit must have arisen independently 
on three separate occasions in the phyletic history of the Insecta. In order 
to secure a broader comparative basis for a discussion of the fungus-grow- 
ing habits of the Attii it will be necessary to summarize our knowledge of 
the similar habits in the termites and ambrosia beetles. 

1. The Fungus-growing Termites. 

Several observers have undoubtedly seen and described the fungus 
gardens of termites without being aware of the full significance of their 
observations. As these gardens are perforated sponge-like masses filled 
with the insects and their brood and lying on the floors of subterranean 
chambers, they have often been regarded as the true nests of the termites. 
The earliest author to call attention to these structures seems to have been 
Konig (1779). After describing the vaulted, smooth- walled earthen cham- 
bers of Termes fatalis at Tanjore, he mentions the gardens full of holes and 
lying on the floors as being "covered with little knots on their outer and 
inner surfaces, like chagrin skin. This texture is most clearly seen at their 
margins near the openings and entrances. Under a magnifying glass, they 
appear fibrous or woolly." In the light of our present knowledge it is 
evident that this fibrous or woolly appearance was caused by the fungus 
mycelium. 



776 Bulletin American Museuvi of Natural History. [Vol. XXIII, 

Smeathman (1781) was the first to recognize the growth covering the 
garden as being that of a fungus, although'he was not aware that' it bore any 
important relation to the insects. In his interesting account of the African 
Termes hellicosus he refers to the gardens as "nurseries." "There is one 
remarkable circumstance attending the nurseries. They are always slightly 
overgrown with mould, and plentifully sprinkled with small white globules 
about the size of a small pin's head. These, at first, Mr. S. took to be the 
eggs; but on bringing them to the microscope, they evidently appeared to 
be a species of mushroom, in shape like our eatable mushroom in the young 
state in which it is pickled. They appear, when whole, white like snow a 
little thawed and then frozen again, and when bruised seem composed of 
an infinite number of pellucid particles,; approaching to oval forms and 
difficult to separate; the mouldiness seems likewise to be the same kind of 
substance. The nurseries are inclosed in chambers of clay, like those which 
contain the provisions, but much larger. In the early state of the nest they 
are not larger than a hazel-nut, but in great hills are often as large as a 
child's head of a year old." I reproduce in Plate LIII, Figs. 55 and 56, 
Smeathman's figures of a "nursery," and of three of the "mushrooms" 
enlarged, as these are the earliest known illustrations of the fungus garden 
of any insect. 

Hagen (1860), in his well-known monograph of the Termitidse, quotes 
a communication which he received from Nietner of Ceylon on a species 
referred to Termes fatalis. This observer describes the vaulted earthen 
chambers of the nest and the fungus gardens which they contained. The 
latter "are hemispherical or broadly conical, flat or concave at the base. 
They are nowhere attached, but stand out freely in the chambers, from 
which they may be removed without injury. They consist of a soft bread- 
like mass.of gnawed wood; are brown in color and when broken open golden 
gray. These nests are always found to be full of minute microscopic fungi, 
the finest and most beautiful imaginable. The corpuscles, as large as a 
fine pin's head and composed of small beads, grow in clusters on a net-work 
of roots and young brood; all resembling crystals of ice or silver." Nietner 
"does not believe that this fungus bears any other relation to the termites 
than that the substance of the nest conduces to its growth. The bread-like 
nests, threaded with fungi, consist of small galleries and cells which often 
contain so many eggs and young that the whole appears to form one living 
mass." 

Although, as shown by these citations, the termite gardens were known 
long before those of the ants, their true significance was not understood till 
after the publication of Moeller's work (1893) on the South American Attii. 
Holtermann in 1899 made the first careful study of the gardens of Termes 



1907.] Wheeler, Fungus-growing Ants of North America. Ill 

taprobanes and fatalis in India and the Malay ■ Archipelago (Singapore, 
Java and Borneo . ) He says : ' ' These animals build their nests in the ground ; 
once only did I find them nesting in a log. Notwithstanding their clandes- 
tine mode of life, I have been able to investigate hundreds and hundreds 
of their singular habitations, for I was able to find them easily by means of 
a species of Agariciis which was always rooted in a termite nest. It was only 
necessary to follow the stem of the pileus into the earth,- although in some 
cases I had to dig to a depth of a meter." Like Nietner, Holtermann refers 
to the fungus gardens' as "nests." These varied from the size of a walnut 
to that of a man's head and were of a sponge-like structure, full of holes and 
galleries containing termite eggs, larvffi and nymphs. The gardens were 
found resting on the floor of the earthen chambers and were separated from 
the walls by a space as broad as one's finger. They consisted of finely 
comminuted vegetable substances (portions of dead leaves and stems) that 
had passed through the bodies of the termites. Under the microscope 
"the surfaces of the galleries were seen to be covered with a white felt-work 
of mycelium. Usually the hyphre were loosely united but sometimes they 
were combined in strands. The individual hyphre were richly septate but 
showed no 'Schnallenbildung' at the septa." Even with the unaided eye 
Holtermann could detect aerial hyphre projecting from the general felt- 
work of the mycelium. "The terminal and often the penultimate cells 
of these hyphre were filled , with strongly refractive, hyaline protoplasm, 
whereas the remaining cells contained remarkably little plasma. The 
terminal cells were often swollen and club-shaped. Sometimes the tip 
even became spherical but only in its upper portion. In exceptional cases 
the hyphre anastomosed, most frequently through confluence of the terminal 
cells." This mycelium ramified through the whole substratum which it 
perhaps served to bind together. The swollen tips of the hyphre were often 
aggregated to form bromatia like those of Atta, but Holtermann failed to 
find them in all termite colonies, and believes that they may occur only in 
the gardens of certain species. In addition to these structures he describes 
others of a more interesting character, namely, small spherical bodies dis- 
tributed everywhere on the mycelial net-work. They were white, varied 
from .25-2 mm. in diameter and were usually attached by a peduncle .5-1 
mm. in length. The minute structure of these spherules which were not 
abundant in the interior of the garden, is described as follows: "The pe- 
duncle consisting of nearly parallel hyphre becomes wider below and loses 
itself in the substratum; otherwise it is of uniform thickness and the head 
is sharply marked off from its end. The rudiment of the head appears as 
a distinct thickening at the tip of the stem and as soon as the head is estab- 
lished the stem ceases to grow. In every chamber are found all the transi- 



778 Bulletin American Museum of Natural History. [Vol. XXIII, 

tions from completed heads to their earliesti development in the form of 
a rich branching at the tip of the bundle of hyphse forming the stem. The 
otherwise parallel filaments ramify more and more, till the head is formed. 
It should be noted that the ends of the filaments do not become thinner 
while branching but always retain the thickness of the general mycelium. 
The outer cells grow less rapidly than the others and after a time become 
passive, thus forming an envelope which later appears as a kind of peridium. 
The limits of the envelope subsequently become more distinct through the 
gradual drying up of the outer cells. The inner cells, on the contrary, 
actively, proliferate. The head continues to enlarge owing to the numerous 
ramifications of the hyphse, till it has become a sac-like apical thickening. 
With this increase in size its spherical form changes to an o-\'al. Some time 
before it attains its complete development, a rapid formation of oidia takes 
place in its interior, as the hyphse break up into verj- short oval cells. Only 
here and there a few of the main filaments remain intact, but the lateral 
branches and greater portion of the hyphse everywhere break up into short 
rows of oidia." These oidia are 8—25 p. long and 6-10 /i broad and have one 
or two vacuoles in their protoplasm. So complete is this resolution of the 
hyphse of the head into oidia that a slight pressure on the cover glass causes 
the dry peridium to burst and thousands of oidia to escape. Holtermann 
found that' the oidia are eaten by the termites, but he expressly states that 
these insects also feed on dead leaves, stems, etc. When the insects are 
removed from the garden, the cavities of the latter become stufl:'ed with 
masses of aerial hyphse, the ripe oidial heads wither up and alien fungi may 
make their appearance. Holtermann does not believe that the termites 
are instrumental in preventing these changes under normal conditions 
since they occur even when termites are present, if the garden is exposed 
to the light. The normal condition of the gardens may be due to their 
confinement in dark subterranean chambers, where the spores of alien fungi 
are unable to germinate. Holtermann is also of the opinion that the above 
described fungus represents a form of the mushroom which he found growing 
out of the nests and calls Agaricus rajap. This mushroom has an umber- 
brown pileus and long gray stem. Its spores are rose-red. He succeeded 
in growing these spores in a culture liquid, but no oidial heads were pro- 
duced ■ although the hyphse sometimes bore club-shaped swellings. Oidia 
from the terrnite gardens were also sown and slowly produced hyphse with 
swollen ends and indistinguishable from those grown from the Agaricus 
spores. This is not, however, conclusive proof of the identity of the two 
fungi, although it seems to be regarded as such by Holtermann. 

Karawaiew (1901) has published in Russian an account of this same 
fungus which he observed at Buitenzorg, Java. His article is accompanied 



1907.] Wheeler, Fungus-groiving Ants of North America. ;: j^ 779 

by some excellent photogravures of the fungus gardens. In Plate LIII, 
Fig. 57, I have reproduced a portion of one of his figures showing the 
small o'idial heads apparent!}' of the natural size. 

Knuth (1899) observed the fungus gardens of a couple of unidentified 
species of Termes at Buitenzorg, but his description is very meager. 

Mme. Errington de la Croix (1900) has published some notes on the 
Malaccan Termes carhonarius which show that the nests of this species 
contain fungus gardens, although they were not recognized as such. She 
merely states that they were " formed (perhaps ?) by agglomerated eggs in a 
nutritive substance." 

Haviland (1902) figures the nest and gardens of Termes malayanus and 
mentions a number of species of this genus from Africa and southern Asia 
as fungus growers. These comprise the species of the hellicosus group 
(r. hellicosus, dives, fatalis, gilvus, azarelli, carhonarius, malaccensis, mal- 
ayanus, natalensis), of the vulgaris group {T. vulgaris, angustaius, capensis, 
taprohanes, badius, latericius), and of the incertus group {T. incertus and 
pallidus). Among these are the largest forms of the genus. He states that 
neoteinic forms, that is, fertile males and females which never develop wings, 
are not known to occur among fungus-growing termites. The soldiers of 
some of the species are aggressive and able to make sounds, thus reca:lling the 
behavior of the Atta soldiers. He says "In the section of the fungus-growers 
to which T. hellicosus belongs the workers run away to their subterranean 
passages when the nest is being opened, whilst the soldiers stay to defend 
the nest; generally the smaller soldiers are more active than the larger, for 
they run about whilst the larger occupy the crevices of the nest and the 
cavities of the fungus beds, where they wait and bite at anything which comes 
v/ithin reach. The soldiers of this group can generally produce the rattling 
sound. In this accomplishment, T. carhonarius has reached the highest 
■ stage of development for the soldiers can hammer in rhythmic unison. At 
first a few begin irregularly, then they get into time, and the others take it up. 
Every soldier in the exposed portion of the nest stands up and hammers with 
its head; the blow is given thrice in very quick succession, and then there 
is an interval of two seconds. The noise they produce reminded me of 
wavelets lapping on a shore. This trick of hammering is seen in only a few 
species ; it is clearly a modification of the shaking movements so often seen 
in workers." 

Sjostedt (1896, 1900, 1903, 1904) has added a number of species to the 
list of fungus-growing termites from Africa. Such are, for example, Termes 
lilljehorgi and the allied goliath, gahonensis, nohilis, amphis, gratus and 
vitrialatus. According to his latest paper (1904) T. transvaalensis is also 
to be included in this series of forms. In his monograph on the African 



780 Bulletin American Museum of Natural History. [Vol. XXIII, 

termites (1900) he figures the gardens of Eutermes heterodon and describes 
them as follows: "May 30, 1891, while digging in a hill-slope near the 
factory N'dian just beside the water fall of the N'dian River a considerable 
number of the fungus gardens of this species were unearthed. They were 
as large as walnuts or somewhat smaller and of a light brownish yellow 
color. They were scattered about in the earth, some a few inches below the 
surface, others somewhat deeper. The earth between them was perforated 
with a net -work of galleries, which connected the different beds with one 
another. Each of the latter was lying free in a cavity so that the termites 
could move about over it without obstruction. Only here and there were 
they attached to the adjacent earthen wall. The nest or fungus garden 
itself is rather fragile and made up of morel-like, folded, and rounded disks 
separated by a labyrinth of long ventricose or more rarely rounded cavities. 
The surface is lumpy and shows that the whole consists of spherical particles. 
The cavities are filled with milkwhite larvae, workers, and soldiers, the two 
latter with yellowish brown heads." Sjostedt's figures of the gardens of 
E. heterodon are reproduced in Plate LIII, Fgs. 60 and 61. 

In 1904 Tragilrdh published an interesting account of three fungus- 
growing termites from the Sudan (T. natalensis, vulgaris and trwgardhi). 
The first builds large conical earthen mounds .8-2.1 m. in height and 1.4 
-5.5 m. in diameter at the base. There are no openings on the surface of 
these mounds, but within they have a number of large chambers, of which 
only the peripheral ones contain fungus gardens. These are like sponges 
and conform in shape to the earthen cavities on the floors of which they lie. 
They are perforated with galleries and consist exclusively of finely com- 
minuted vegetable substances that have been yoided and welded together 
by the insects, for under the microscope they are seen to be made up of pellets 
that have been flattened into lenticular forms. The fungus growth is de- 
scribed as follows: "Under the microscope the surface of the substratum 
is seen to be covered with a white felt-work of mycelium and under still 
higher magnification small hyphfe may be detected. These are aggregated 
here and there to form small round plates as much as I mm. in diameter 
and consisting of dense branched hyphfe. These apparently correspond 
to the structures mentioned and described by Holtermann, but differ from 
these, so far as I have been able to observe, in not having the tips of the 
hyphfe swollen. Here and there on the inner walls, usually not in any 
great abundance, but more sporadic, at least in the gardens I have examined, 
there are small round bodies, which may be as much as 2.5 mm. in diameter. 
They are of a brilliant white color and are unlike those mentioned by Holter- 
mann in always lacking a peduncle. These spherules are of rather solid 
consistency and have an external tougher envelope, the whole forming a 



1907.] Wheeler, Fungus-growing Ants of North America. 781 

compact mass of very much branched and contorted hyphse. The formation 
of the oidia, or process whereby, according to Hohermann, the hyphse in 
the interior of the spherules breaks up almost completely into very short 
oval cells, is by no means so complete in our species. To be sure, the 
hyphae are constricted in the interior so that they appear as rows of short 
oval cells, completely filled with protoplasm, but these cells even in the larg- 
est spherules, which have reached their full development, .remain attached 
to one another so that when a thin section is pressed under the cover glass, 
only a few of the cells escape. In the spherules described by Holtermann, 
on the contrary, slight pressure on the cover-glass sets free thousands of 
bidia." 

The mounds of. T: vulgaris (= affinis TragS,rdh) are as large as those of 
natalensis (1.4 m. high and 5.5 m. in diameter at the base), but the structure 
and arrangement of the chambers is very different. They are separated 
by thick walls and communicate with one another by very tenuous galleries. 
Each chamber has a flat floor with a peripheral groove and an arched roof. 
The gardens, which are shaped like inverted dishes and are not confined to 
the smaller peripheral chambers, are often concave beneath, with a ridge 
around their border fitting into the circular groove in the floor of the chamber. 
The substratum consists of the same materials as in natalensis and is per- 
forated with numerous transverse galleries. Concerning the fungus Trii- 
g§,rdh says: "The spherules are much smaller than in natalensis, are like 
these nonpedunculate, and occur in great numbers on the walls and espe- 
cially on the roofs of the cavities and galleries in the peripheral portions of 
the gardens. These portions are also stuffed with larvce and nymphs. The 
spherules are unlike those of T . natalensis in structure, since as shown in 
Figs. 2 & 3 PI. Ill [reproduced in the present paper as Figs. 58 & 59, PI. 
LIII], the cells in the outer layer of the spherules are larger than those in 
the interior. Both the inner rows of cells, which ramify dichotomously, 
and the outer ones, are in part empty, in part filled with finely granular proto- 
plasm." ^Although Trag^rdh found fungus-gardens in the nests of T. 
troegardhi (= incertus Tragh..) which seems to live as an inquiline in the nests 
of T. bellicosus, natalensis and vulgaris, he believes that these had been 
stolen from the host termites and that trcegardhi does not itself grow .fungi. 

Doflein (1905, 1906) has contributed more recent observations on the 
gardens of termites. He studied colonies of T. obscuriceps in Ceylon. 
The mounds of this species are about 2 m. high and terminate above in one 
or more huge tubular, chimney-like orifices which open into the galleries 
and chambers in the interior of the nest. The chambers are about as large 
as a cocoa-nut or smaller, with smooth walls and excavated to a depth of 
1 J m. below the surface. The gardens, which consist of comminuted wood 



782 Bulletin American Museum of Natural History. [Vol. XXIII, 

that has passed through the bodies of the insects, are dish-shaped, and there 
may be several piled one on top of the other. in a single chamber. They 
are perforated with galleries filled with the termites and their larvfe. "On 
taking one of these brown cakes in the hand, one can see with the unaided 
eyes that its whole surface is covered with a fine bloom of fungus mycelium. 
When broken open the interior of the galleries is found to be covered with 
peculiar white spherules about as large as a pin-head (1-2 mm. in diam.)." 
Doflein's description of the minute structure of these spherules is less 
explicit than that of Holtermann and Trag3,rdh, but he actually saw the 
termites swallow these bodies when they were presented on the point of 
a sterilized needle. They were eaten by the larval workers and soldiers 
and by the adult kings and queens, but the adult workers and soldiers would 
not take them. The intestines of the latter contained only comminuted 
wood in which no fungus elements could be found. Doflein, is, therefore, 
of the opinion "that in this species the larvae are fed with a concentrated 
and easily assimilated food in the form of mycelial spherules, and that these 
constitute the permanent food of the sexual forms, whereas the larvse of 
the workers and soldiers are not fed with these after reaching a certain age 
but with other substances [dead wood] instead. This suggests the further 
inference that this food raay play an. important role in the differentiation 
of the castes of Termes obscuriceps Wasmann." 

Doflein found that when the fungus garden of this insect is placed in 
the light under a bell- jar to protect it from evaporation "the termite fungus 
can easily be induced to fructify, a peculiarity in which it differs from the 
fungus cultivated by the South American leaf-cutting ants. In the course 
of a few days numerous long, club-shaped fruiting organs grow up out of 
the dense mass of hyphse, which has developed in the meantime. As time 
goes on these club-shaped bodies develop pilei, which, as Mr. Green of Pera- 
denyia informs me, are now known to be those of an Agaricus, a fact which 
is also indicated by my own observations. While the fungus is growing up 
freely in this manner, one is surprised to find alien fungi gradually making 
their appearance in the garden, and other objects in the neighborhood taking 
on the usual mouldiness. The tendency of the termite fungus to grow as a 
pure culture must therefore be very great. This is the case even when very 
few termites are present. Hence the purity of the culture cannot be ascribed 
to a ceaseless weeding process carried on by the termite workers, like that 
assumed by Moeller in the case of the South American Attas." 

When the garden is left under the bell-jar the under surface of the latter 
soon becomes wet, showing that the fungus gives off a great deal of water. 
In a day or two the termites become suffocated, although masses of these 
Insects herrhetically sealed between pairs of watch glasses manage to live in 



1907.] Wheeler, Fungus-growing Ants of North America. 783 

perfect condition. On raising the bell-jar a peculiar odor is noticeable, 
which Doflein believes to be a gas fatal to the insects. In the wild nests this 
gas must be carried off by the chimneys which thus act as ventilating shafts. 
All of the foregoing observations relate to Old World Termites. One 
is naturally led to inquire whether any of the American species raise mush- 
rooms. Haviland was of the opinion that certain of the South American 
forms such as T. dims are "almost certainly fungus growers." The only 
observations I have found on the habits of this species are contained in 
Silvestri's work (1903). He, says: "I have seen in the galleries (Fig. 298) 
pieces of grass 10 mm. long, of leaves 6-10 mm. long and twigs 30 mm. long 
and 2 mm. in diameter. I have found such materials accumulated in small 
quantities at various points in the galleries, but I believe that they are not 
utilized in this form but are brought together in some more subterranean 
portion of the nest for the development of a fungus on the mycelium of which 
the termites feed." He found similar vegetable fragments in the nests of 
T. grandis and molestus. Of the latter species he says: "I was unable to 
reach the center of the nest, but I succeeded in finding small masses of grass 
with the mycelium already developed." From these, which he figures, he 
concludes that the species grows fungi. But these observations are by no 
means conclusive as is evident from a comparison with the above cited 
observations on the Old World species. These do not raise fungi on pieces 
of dead leaves, twigs, etc., but on finely comminuted particles voided from 
the alimentary canal and built up in the form of a sponge. . Moreover the 
temporary stores of leaves, etc. which are brought into the nests as food may 
easily mould when left in the moist galleries. We may conclude therefore 
that there is really nothing in Silvestri's observations to prove that any of 
the South American termites eat and grow fungi. 

The most important study of the fungus-growing termites has been 
recently contributed by Fetch (1906). Unfortunately I could not consult 
this work till after the present article had gone to press, so that I am unable 
to review it at length. Fetch carefully investigated the habits and fungus 
gardens of the Ceylonese Terines obscwiceps W'asm. and T. redemanni 
Wasm. In several particulars his account differs from those of Holtermann 
and Doflein. I quote from the summary of his beautifully illustrated paper 
the passages relating to the fungi for the purpose of showing how complex 
and difficult are the problems with which the mycologist is confronted in 
any critical study of the fungus-growing insects. After describing the 
sponge-like combs in the chambers of the nest, he says ■} 

"The mycelium on the comb bears small white, stalked or almost sessile 

• In the quotation I have omitted the numerals belonging to the paragraphs and have 
run the latter together. 



784 Bulletin American Museum of Natural History. [Vol. XXIIl, 

'spheres.' These consist of branching hyphse bearing either spherical or 
oval cells. The spherical cells do not germinate. The oval cells germinate 
readily, but it has not been possible to reproduce the 'spheres' from them. 
When the comb is old an .agaric grows from it. This agaric appears in two 
forms, one of which has been assigned by various mycologists to Lentinus, 
Collyiia, Pluteus, Pholiota and Flammula, and the other to Armillaria. It 
develops in a cartilaginous, almost gelatinous, universal veil and is a modified 
Volvaria. Selerenchymatous cells occur at the base of the agaric stalk and 
in aborted agarics. It has not been possible to germinate the spores of the 
agaric or to grow the sphere-producing mycelium from its tissues. When 
the comb is enclosed in a bell jar, Xylaria stromata are produced. Scle- 
rotia may also be formed: the same stromata grow from these. This 
-Xylaria is probably X. nigripes. The shape of the stroma and conidio- 
phore depend on the age of, and amount of moisture in, the comb. When 
sown on agar the spores of these reproduce the Xylaria stromata. These 
stromata occur most abundantly in combs which have produced an agaric. 
After continued rain Xylaria nigripes grows from deserted termite nests. 
Other fungi which grow on combs removed from the nest include Mucor, 
Tliamnidium, Cephalosporium, Peziza. As these are not' found in the nest 
though some of them are capable of dcvelopracnt under ground, it is prob- 
able that the termites 'weed out' foreign fungi from the cultivation of the 
comb. The comb material is probably sterilized by its passage through the 
alimentary canal. That the 'spheres' form the food of the termites is 
probable, as in the ca,se of the leaf -cutting ants : neither case can be con- 
sidered definitely proved. Termes redemanni and T. obscuriceps undoubt- 
edly prefer fungi, or wood which has been attacked by fungi. Whether a 
difl^erence in food causes the differentiation of termites into workers, 
soldiers, and sexed insects, is not decided. , A Ceylon agaric, Entoloma 
microcarpum, possesses a mycelium composed of spheres of swollen cells: 
the details of these spheres resemble the parts of the termite spheres, but 
are not so highly developed. It is most probable that the 'spheres' in the 
termite comb and the ' Kohlrabihauf clien ' of the leaf -cutting ants investi- 
gated by Moeller are parts of a normal mycelium, and that their shape is 
modified by the insects only in a very slight degree, if at all. The available 
evidence appears to show that the ' spheres ' are part of the mycelium of the 
Volvaria, but it has not been possible to connect these forms experimentally." 
A review covering some other features of Fetch's work has just been published 
by Harris in the American Naturalist (1907). . 

The foregoing accounts from several observers show that the fungus- 
growing termites differ from the Attiine ants in several important particulars. 
In the first place the termites use their own excrement as a substratum. 



1907.] Wheeler, Fungus-growing Ants of North America,' 785 

moulding it into the form of a sponge containing numerous habitable cham- 
bers and galleries. This substance is, of course, much harder and more 
compact than the comminuted leaves, etc., employed by the Attii. Second, 
the fungus grown on this substratum forms bromatia (the spherules or oidial 
heads) of a ver}' different type from those found in the gardens of the Attii. 
And third, the termites that are in the habit of growing fungi are not exclu- 
sively mycetophagous like the Attii, but subsist also and probably very 
largely on dead wood, twigs and leaves. If it be true as Holtermann and 
Doflein believe, that the termites are not instrumental in maintaining the 
purity of the fungus culture, we should have another striking difference, but 
it is quite conceivable that both in the termites and the ants some efHuvise 
emanating from the myriads of insect bodies may be responsible not only 
for the suppression of alien fungi but also for the aberrant growth of the 
food-plant. 

I have already called attention to the fact that Holtermann cannot be 
said to have demonstrated that the Agaricus rajap is the fruiting form of the 
fungus which grows in the gardens as a mycelium with oidial spherules. 
And Doflein's and Fetch's observations are open to similar doubts. Not 
only is there no satisfactory proof that the termite fungus is a basidiomycete, 
but the same is true also of Moeller's statement that the South American Attw 
cultivate the mycelium of a fungus (Rozites gongylophora) belonging to the 
same group. A careful perusal of Moeller's observations shows an important 
lacuna at this point. That his Attce ate portions of the pileus and stem of the 
Rozites does not prove that it is the fruiting form belonging to the fungus they 
habitually cultivate and eat. Nor is Moeller on much surer ground when he 
assumes that the mycelia cultivated by different genera of Attii belong to 
different species of fungi, for it is very probable that the ants of one species 
would avoid fungus taken from the nest of another on account of the alien 
nest-aura. Certainly, to the human olfactories the fungus gardens of Atta 
texana have a very striking odor which is altogether lacking in the gardens of 
Trachymyrmex, and it would be strange if these differences did not affect 
the appetites of such sensitive insects as the ants. In my opinion, it is not 
improbable that the fungi cultivated both by the termites and ants may be 
more closely related to the moulds (Ascomycetes) than to the mushrooms 
(Basidiomycetes). Moeller does in fact, call attention to certain ascomycete 
peculiarities in the mycelium cultivated by Acromyrmex discigera. This is 
a matter, however, to be settled by the mycologist, and I merely call attention 
to it in this connection, because Moeller's somewhat guarded statements 
have assumed an unduly positive form in the writings of subsequent reviewers 
of his work. 



786 Bulletin American Museum of Natural History. [Vol. XXIIl 

2. The Ambrosia Beetles. 

The beetles of the family Scol\i;id8e may be divided into two groups 
exhibiting very different ethological peculiarities: the bark-borers, which 
excavate and inhabit tvibular galleries between the.bark and the splint and 
eat the substance of the tree, and the v/ood-borers, or ambrosia beetles, 
which extend their galleries into the wood and subsist on delicate fungi 
growing on their walls. All Scol}i:ida; are of small size and dark color, 
with cylindrical bodies and short legs adapted to the shape and size of their 
galleries (PI. LII, Figs. 62 and 63), but the mouth-parts differ in the two 
groups; the bark-beetles having strong maxillfe armed with 12-20 spine- 
like teeth in adaptation to their hard food, whereas the fungus-eating wood- 
borers have weak maxillae with 3CH40 flexuous bristles. Unlike the Attii 
■ and fungus-growing termites, the wood-borers are not confined to the tropics 
or to a single hemisphere, but are cosmopoliian in their distribution and 
well represented even in the north temperate zone. The species have been 
assigned to a number of genera {Platypus, Gnathotrichus, Trypodejidron, 
Xyleborus, Xyloterus, Corthylus and Eterocydon [Monarthrum]). As these 
Insects are very destructive to wood, they are well known to economic ento- 
mologists, who have described their habits in journals or text-books devoted 
to forestry. The remarkable habits have therefore been little noticed by 
entomologists interested in general biological questions. 

There has been considerable difference of opinion in regard to the feed- 
ing habits of the ambrosia beetles since the time of Schmidberger (1836) 
who believed that Xyleborus dispa^- Fabr. fed on the sap exuding into its 
burrows from the surrounding wood.' The mother beetle was 'supposed 
to mould this sap into a coagulated, albuminoid mass and to feed it to her 
young. This substance Schmidberger called "ambrosia." Various con- 
jectures concerning its nature were expressed by Ratzeburg (1839—1844), 
Altum (1872-1875), and Eichhoff (1881). In 1844 Hartig discovered a 
fungus in the galleries of Xyleborus dispar and described it as Monilia Candida. 
Several years later (1872a, 18726) he described similar conditions in Xylo- 
terus lineatus Oliv., which lives only in conifers, and X. domesticus L., 
which is confined to deciduous trees. In 1895 Goethe ]3ublished, a good 
description and figure of the fungus of X. dispar. At about this time 
Hubbard took up the study of the North American ambrosia beetles and 
published most interesting accounts of their habits (1897a, 1897&). Hop- 
kins, too, who has given special attention to our Scolytidae, has published a 
number of valuable observations (1898-19046), and Hedgcock (1906) has 
made some important observations on the fungi. In the following para- 



1907.] Wheeler, Fungus-growing Ants of North America. 787 

graphs I shall confine myself to an account of the investigations of these 
three authors. 

The ambrosia beetles resemble the ants and termites and differ from 
other Coleoptera in living in societies and in caring for and feeding their 
larvse. The arrangement of the galleries, which have walls stained dark 
by the fungus, differs in different species. Those of Xylehorus celsus Eichh., 
living in the hickory, are shown in PI. LII, Fig. 64, taken from Hopkins 
(1904). The galleries ramify into the sap wood from a single entrance 
gallery that opens on the bark. These perforations do not necessarily kill 
the tree, but they spoil the wood for many commercial purposes. When 
made in young growing trees they may be overgrown by succeeding layers 
of wood. Hopkins (1903) has given an interesting account of this condi- 
tion in trees infested with the Columbian timber-beetle {Corthylus colum- 
hianus Hopkins). This beetle which is responsible for losses to the lumber 
interests of North America "amounting to millions of dollars, attacks the 
sap-wood of the young, living, healthy tree, in which the adults excavate 
their brood galleries find deposit their eggs. These hatch and develop 
into beetles and emerge within one year. The next year the operation is 
repeated in another place in the same tree, and so on for hundreds of years, 
or as long as the tree lives, so that the galleries excavated in different years 
and periods occupy their respective positions in the heartwood and sapwood 
of the full-grown and old tree. Nearly all the damage by this insect, as 
affecting the best part of the trees, was done 50, 100, 200 or in some cases, 
as noted in an old tulip tree, over 400 years ago. The age of each gallery 
observed in the end of the log is easily determined by counting the number 
of annual layers of wood between the old healed-over entrance to the galleries 
and the bark. Within recent years, examples of the species which do this 
work have been exceedingly scarce; consequently but little evidence of its 
work can now be found in the sapwood and outer heartwood of living trees. 
Therefore there is no remedy for the old work and probably no need of 
trying to combat an insect which is apparently becoming extinct." 

Hubbard's general account (1897a) of the fungus growing habits of the 
ambrosia beetles is worth quoting in extenso, as it is one of the most impor- 
tant of recent contributions to the study of insect ethology: "A small frag- 
ment of ambrosia taken from the gallery of any species of these timber 
beetles, if placed on a glass slide, with a drop of water or glycerine and 
examined with an objective of moderate power, is plainly seen to be a fungus. 
It will be found, however, that the different kinds of ambrosia fungi are con- 
nected with certain species of the beetles irrespective of the sort of timber 
in which the galleries are constructed. So far as we yet know the food of 
each species of ambrosia beetle? is limited to a certain kind of ambrosia, 
and only the most closely related species have the same food fungus. 



788 Bulletin American Museum of Natural History. [Vol. XXIII, 

"Two principal types exist among the varied forms of these minute 
fungi: (1) Those with erect stems, having at the termination of the stems, 
or their branches swollen cells (conidia) : [PI. LII, Fig. 65]. (2) Those 
which form tangled chains of cells resembling the piled-up beads of a broken 
necklace. The erect or stylate forms are found among those species of the 
beetles whose larvse live free in the galleries {Platypus and Xylehorus). The 
bead-like or moniliform kinds appear to be peculiar to the species whose 
larvae are reared in separate cells or cradles (Corthylus, Monarthrum, etc.). 
"All the growing parts of the fungus are extremely succulent and tender. 
The conidia especially ate always pellucid, and glisten like drops of dew. 
When the plant is in active growth, conidia are produced in the greatest 
abundance, growing sometimes singly, at the end of short straight stems, 
sometimes in grape-like clusters among interlacing branches. At such 
periods the fungus appears upon the walls of the galleries like a coating 
of hoarfrost. The young larvae nip off these tender tips as calves crop the 
heads of clover, but the older larvae and the adult beetles eat the whole struc- 
ture dawn to the base, from which it soon springs up afresh, appearing in 
little white tesselations upon the walls. 

"The gro'tt'th of ambrosia may in fact be compared to asparagus, which 
remains succulent and edibl? only when continually cropped, but if allowed 
to go to seed is no longer useful as food. In like manner the ambrosia fungus 
must be constantly kept in fresh growth, otherwise it ripens; its cells burst 
and discharge the protoplasmic granules, which they contain in myriads, 
and the entire plant disappears as if overwhelmed by a ferment. 

"Various disturbances of the conditions -necessary to its growth are apt 
to promote the ripening of the fungus, and this is a danger to which every 
colony of ambrosia beetles is exposed. If through any casualty the natural 
increase of a populous colony is checked, there results at once an overpro- 
duction of the ambrosia. It accumulates, ripens, and discharges its spores, 
choking the galleries and often suffocating the remaining inhabitants in 
' their own food material. The same results may sometimes be brought 
about by closing the, outlets of the galleries through the bark, or by spraying 
into them kerosene or some other noxious liquid. The inmates of the 
■colony are thereby thrown into a panic, the beetles rush hither and thither 
through the galleries, trampling upon and crushing young larvae and eggs, 
breaking down the delicate lining of ambrosia on the walls of the brood 
chambers and puddling it into a kind of a slush, which is pushed along and 
accumulated in the passage ways, completely stopping them in places. 
The breaking down of the food fungus follows and in a few days the galleries 
are filled with a paste-like ma:ss of granules or spores, or with threads of 
mycelium, in which the living insects are suffocated and destroyed. 



1907.] Wheeler, Fungus-growing Ants of North America. 789 

"The ambrosia does not make its appearance by accident or at. random 
in the galleries of the beetles. Its origin is entirely under the control of the 
insect. It is started by the mother beetle upon a carefully packed bed or 
layer of chips, sometimes near the entrance, in the bark, but generally at the 
end of a branch gallery in the wood. In some species the ambrosia is grown 
only in certain brood chambers of peculiar construction. In others it is 
propagated in beds, near the cradles of the larvee. The excrement of the 
larvae is used in some and probably in all species to form new beds or layers 
for the propagation of the fungus. ■ ' ' 

"It is not alone, however, the excreta of the living beetles or their young 
that is required for the development of ambrosia; there must be present a 
certain amount of moisture or sap, and the sap in most species must be in a 
condition of fermentation. Certain ambrosia beetles, as for example the 
species of Corthylus, seem not to need fermentation in the propagation of 
their fungus; their galleries are constructed in the sap-wood of vigorous 
plants. The great majority of the species, however, attack the wood of such 
trees only as are moribund; in which the natural circulation of the sap has 
ceased, and fermentation has begun. Some of the number are also able 
to produce their food fungus in wood which is saturated with a vinous or 
alcoholic ferment, and they attack wine and ale casks, perforating the 
staves with their galleries and causing serious loss by leakage. 

"The precarious conditions under which their food is produced limit 
the life of a colony of ambrosia eaters in most cases to a single generation. 

"Under favorable conditions, , and in large tree trunks, colonies may 
continue their excavations during two or three generations before the failure 
of the sap or change in its condition puts an end to their existence and 
forces the adult beetles to seek new quarters. 

"When iheir galleries are disturbed and opened to daylight, the adult 
beetles generally fall to eating their ambrosia as rapidly as possible. Like 
other social insects they show their concern at the threatened loss of their 
most precious possession and try to save it, just as bees, when alarmed, fill 
themselves with honey. . 

"As its honey is to the bee, so to the ambrosia-feeding beetle its food 
fungus is the material the propagation and preservation of which is the 
chief concern of its life. Its solicitude concerning it is not surprising when 
one considers the herculean labors which it undergoes in the effort to pro- 
duce it, the frequent failures, and the difficulties and uncertainties that at all 
times attend its preservation in the vegetative form, in which alone it can 
serve the insect as food." 

The life-histories of the ambrosia beetles described and copiously illus- 
trated by Hubbard suggest a wide range of habits within the group. T'hc 



790 Bulletin Americmi Museum of 'Natural History. [Vol. XXIII, 

genus Platypus, though best represented in- the tropics, contains several of 
the largest and most destructive species in the United States. "They are 
powerful excavators, generally selecting the trunks of large trees and driv- 
ing their galleries deep into the lieart-\A"ood. They do not attack healthy 
trees but are attracted only by the fermenting of the sap of dying or very 
badly injured trees. The death rattle is not more ominous of dissolution 
■ in animals than the presence of these beetles in standing timber. . . .The 
. female is frequently accompanied by several males and as they are sav-age 
fighters, fierce sexual contests takcs^place, as a result of Vv'hich the galleries 
are often strewn with the fragments of^the vanquished. The projecting 
spines at the end of the wing-cases are very\ffective weapons in these fights. 
With their aid a beetle attacked in the rear can make a good defense and fre- 
quently by a lucky stroke is able to dislocate the outstretched neck of his 
enemy. The females produce from 100 to 200 elongate-oval pearl-white 
eggs, which they deposit, in clusters of 10 or 12, loosely in the galleries. 
The young require five or six weeks for their development. They v.'ander 
about in the passages and feed in company upon the ambrosia which grows 
here and there upon the walls. . , .The older larvse assist in excavating the 
galleries, but they do not eat or swallow the wood. The larvae of all ages 
are surprisingly alert, active and intelligent. They exhibit curiosity equally 
with the adults, or show evident regard for the eggs and very tender young, 
which are scattered at random about the passages, and might easily be 
destroyed by them in their movements. If thrown into a panic the young 
larvae scurry away with an undulatory movement of their bodies, but the 
older larvffi will frequently stop at the nearest intersecting passage and 
show fight to cover their retreat." The ambrosia of P. compositus Say 
consists of hemispherical conidia growing in clusters on branching stems. 
The long continued grovvth of this fungus blackens the walls of the older 
galleries. 

Xylehorus saxeseni Ratzb., instead of producing- ramifying galleries, 
excavates in hardwood trees (oak, hickory, beech, maple) a flat, leaf-shaped 
brood chamber connected with the surface of the bark by one or a few 
tubular galleries. The chamber "stands vertically on edge, parallel with 
the grain of the wood. The space between the walls is not much greater 
than the thickness of the bodies of the adult beetles. The larvaj of all ages 
are able to cling to the vertical walls, and to progress over them by an adapta- 
tion of the end of the body which aids them in progression. The entire 
surfaces of the walls in the brood cJiamber are plastered over with ambrosia 
fungus. It consists of short erect stems, terminating in spherical conidia. 
The freshly grown fungus is as colorless as crystal, but it is usually more 
or less stained with greenish yellow, and sometimes resembles a coating 



1907.] Wheeler, Fungus-growing Atits of North America. 791 

of sublimed sulphur. The brood chamber is packed at times with eggs, 
larvee, pupse and adults in all stages of maturity. The larvse aid in extend- 
ing the brood chamber. They swallow the wood which they remove with 
their jaws, and in passing through their bodies it becomes stained a mustard- 
yellow color. Great quantities of this excrement are ejected from the open- 
ings of the colony, but a portion is retained and plastered upon the walls, 
where it serves as a bed upon which there springs up a new crop of the food 
fungus. In populous colonies it is not unusual to find the remains of individ- 
uals which have died packed away in^a deep recess of the brood chamber 
and carefully inclosed with a walLof chips." Hubbard found one of these 
catacombs containing "the multilated bodies of a dozen or more larvse 
and immature imagoes, together with the fragments of a predatory beetle, 
Colydium lineola Say." In a short branch gallery of the same chamber he 
also found the lifeless body of the mother of the colony carefully sealed up 
by the surviving insects. 

In the species of Pterocychn, Xyloberus and Gnathotrichus the young are 
reared in cradles, or short diverticula of the main galleries, and fed by the 
mother beetles. In species of Ptercychn (inali Fitch and jasciatum Say) 
"the sexes are alike, and the males assist the females in forming new colonies. 
The young are raised in separate pits or cradles which they never leave until 
they reach the adult stage. The galleries, constructed by the mature 
female beetles, extend rather deeply into the wood, with their branches 
mostly in a horizontal plane. The mother beetle deposits her eggs singly 
in circular pits which she excavates in the gallery in two opposite series, 
parallel with the grain of the wood. The eggs are loosely packed in the 
pits with chips and material taken from the fungus bed which she has pre- 
viously prepared in the vicinity and upon which the ambrosia has begun to 
grow. The young larvse, as soon as they hatch out, eat the fungus from these 
chips and eject the refuse from their cradles. At first they lie curled up in 
the pit made by the mother, but as they grow larger, with their own jaws 
they deepen their cradles, until, at full growth, they slightly exceed the 
length of the larvse when fully extended. The larvse swallow the wood 
which they excavate, but do not digest it. It passes through the intestines 
unchanged in cellular texture, but cemented by the excrement into pellets 
and stained a yellowish color. The pellets of excrement are not allowed 
by the larvse to accumulate in their cradles, but are frequently ejected by 
them and are removed and cast out of the mouth of the borings by the 
mother beetle. A portion of the excrement is evidently utilized to form the 
fungus bed. The mother beetle is constantly in attendance upon her young 
during the period of their development, and guards them with jealous care. 
The mouth of each cradle is closed with a plug of the food fungus, and as 



792 Bulletin American Museum of Natural History. ' [Vol. XXIII, 

fast as this is consumed it is renewed with fresh material. The larvae from 
time to time perforate this plug and clean out their cells, pushing out the 
pellets of excrement through the opening. This d6bris is promptly removed 
by the mother and the opening again sealed with ambrosia. The young 
transform to perfect beetles before leaving their cradles and emerging into 
the galleries." The ambrosia of Pterocydon "is moniliform. and resembles 
a mass of pearly beads. ..In its incipient stages a formative stem is seen, 
which has short joints that become globular conidia and break apart. Short 
chains of cells, sometimes showing branches, may often be separated from 
the mass; The base of the fungus mass_is stained with a tinge of green, 
but the stain on the wood is almost black." ^"^^ 

In Xylotencs returns Lee, which lives in the broad-toothed aspen {Popu- 
lus grandidentata) of the northern States, and is the largest of our ambrosia 
beetles, still other peculiarities are observable. "Several pairs of the beetle 
unite in colonies having a single entrance, but each family occupies its own 
quarters, consisting of one or two branch galleries. The galleries do not 
penetrate deeply into the heart -wood. Each female attends her own brood, 
which are raised in cradles extending upward and downward at right angles 
to the main passage-way. She feeds the young with a yellowish ambrosia 
grown in beds in the neighborhood of the cradles. . The mouth of each cradle 
is constantly kept filled with a plug of the- food fungus.. The ambrosia 
consists of oval -cells which form upright sticks resembling some forms of 
styliform ambrosia, but they do not branch and are capable of being broken 
up into beadlike masses without losing fheir vegetative powers. Although 
the color of the fungus is yellowish, the galleries are stained intensely black." 

The foregoing account of the ambrosia beetles suggests a number of 
intricate and important problems for future investigation. That these 
insects have developed unusually advanced social habits for Coleoptera is 
certain. It is also evident that the fungi which they culrfvate are not basi- 
diomycetes but chromatogenic or wood-staining ascomycetes. Hedgcock 
(.1906) who has recently studied these fungi, describes a number of species 
referable to the genera Ceratostomella (wood-bluing), Graphium, liormoden- 
dr.on, Plormiscivm (wood blackening and wood-browning), Penicillium and 
Fusarium (wood-reddening). Cultures of one of the species {Graphium, 
amhrosiigerum Hedge.) were made from material taken from the burrows 
of ambrosia beetles in the wood of Pinus arizonica Eng. The mycelium 
was seen to develop stromata with heads, and both primary and secondary 
conidia, but the author records no observations on the relations of the 
beetle to the fungus or the modifications produced in the food plant when in 
the presence of the insect. From some investigations now in progress at 
the Eoyal School of Forestry at Tharandt, Saxony, and communicated to 



1907.] Wheeler, Fungus-growing Ants of North America. . 793 

me by Professors K. Escherich and F. W. Neger it wovild seem that in the 
case of the ambrosia beetle Trypodendron lineatus the fungus is found only 
in the mycelial and conidial stages when tlie insects are present, but that 
when these have been removed stromata with globular or flattened heads, 
similar to those figured by Hedgcock for Graphium alrovirens and ambrosii- 
geriim,.aie produced on the walls of the galleries. 

The constant association of certain species of ambrosia beetles with 
certain species of fungi, irrespective of the kind of wood on which they 
grow, indicates that the mother beetles must be instrumental in transferring 
the plant from colony to colony and from tree to tree in some manner analo- 
gous to the fungus transfer of the Atia queen when establishing her for- 
micary. Hedgcock seems to have found evidence of some such transference 
of Ceratosfomella conidia. He says: "These are readily disseminated by 
the wind and are probably carried by insects which penetrate the wood 
and bark of trees, like most of the ambrosia and bark beetles. At the stage 
in which the conidia form a mucilaginous mass, they adhere readily to any 
insect that may, pass over them. In the laboratory a number of species of 
mites which feed on fungi carried spores on their bodies from colony to colony 
in an agar plate to a sterile portion of the surface of the medium and started 
new colonies of the fungus. Bark beetles were placed in a dish with the 
conidial stage of CeratostomeUa and after allowing them to remain a short 
time were transferred to sterile agar plates which were inoculated with spores 
from the insects. It is probable that some species of insects feed on the 
conidial stage of CeratostomeUa, especially one or more species of ambrosia 
beetles and a number of mites infesting their channels in the wood; but 
proof is yet lacking on this point. The constant occurrence of this fungus 
in the channels of a number of wood boring beetles indicates that the co- 
nidia or the ascospores must be carried in some manner by these insects," 

Interesting as are the observations on the fungicolous ants, termites and 
beetles collated in the preceding pages, we must admit that they are still frag- 
mentary and leave many fundamental questions unanswered. It will be 
seen that our knowledge of the fungi cultivated by all three of these insect 
groups is very unsatisfactory and that many more investigations must be 
undertaken before we shall be able to determine the precise taxonomic 
affinities of the plants and to estimate the extent of the modifications induced 
in their growth by the symbiotic insects. Equally fragmentary is our knowl- 
edge of the phylogenetic origin and development of the fungus-growing 
habit. Indeed, this problem in the termites and ambrosia beetles has 
scarcely been recognized a yet. The views that have been entertained in 
regard to the phylogeny of the Attii and their habits are perhaps, of sufficient 
interest to command attention till further observations are forthcoming. 



794 • Bulletin American Museum of Natural History. [Vol. XXIII, 

3. The Phylogeny of the Attii and of the Fungus-growing Habit. 

The Attn belong to a complex of Myrmicine genera once grouped to- 
gether as Cryptocerides on account of their superficial resemblance to the 
ants of the genus Cryptocerus. Forel in 1892 was the first to split up this 
artificial group. He divided the genera into four tribes, the first including 
the Attini, the second the Dacetonini, again divisible into three subgroups : 
a, Strumigenys, Orectognathus, Epitritus and possibly Hypopomyrmex; 
h, Daceton and Acanthognathus, and c, Rhopalothrix, Ceratobasis and 
Cataulacus. To a third tribe he assigned Meranoplus and Galyptomyrmex, 
which were recognized as having affinities with the Tetramorii, and to a 
fourth tribe he assigned Cryptocerus and Procryptocerus. In 1893 he said: 
"Taxonomy has proved to me that the Attini are intimately related to the 
Dacetonini (Strumigenys, etc.) and has led me to suppose that the Attini 
are of secondary derivation. This is all the more probable, because they are 
confined to the American continent, whereas the Dacetonini are distributed 
over the whole world, even to New Zealand." 

Emery, writing in the same year (1893), expresses himself somewhat 
more explicitly. "If we separate from the ensemble of the ancient Crypto- 
cerides, on the one hand Cryptocerus and Procryptocerus (group Cryptocerini), 
on the other hand Cataulacus (forming by itself a distinct group), and if 
furthermore, Meranoplus and Calyptomyrmex be attached to Tetramorium 
and its allies, all that remains of M. Forel's Attini may be divided into two 
groups according to the venation of the wings. In the genera Atta, Seri- 
comyrmex, Cyphomyrmex, Glyptomyrmex [Myrmicocryptd], Apterostigma, 
the radial cell is closed and there is no trace of a discal cell nor of a recurrent 
nervure, the trunk "of the cubital nervure being straight or feebly sinuous. 
In the genera Rhopalothrix, Strumigenys and. Epitritus the radial cell is 
open; in the female Rhopalothrix petiolata Mayr I find a vestige of a recur- 
rent nervure, and in the male Strumigenys imitator Mayr the trunk of the 
cubital vein is strongly arcuate behind at the base, indicating the point of 
insertion of a recurrent nervure that has disappeared. According to Smith's 
figures, Daceton, which has a discal cell, belongs to this latter group; 
probably the same is true of Acanthognathus, Ceratobasis and Orectognathus, 
whose wings are still unknown. The former of these two groups, which we 
may call the Attini genuini is exclusively American, whei'cas the latter, 
which niay bear the name Dacetini, is represented in all the zoological regions 
except the Ethiopian. These two groups are, however, very closely allied, 
and the fossil genus Hypopomyrmex, which undoubtedly approaches the 
ancestors of Strumigenys very closely, has a discal and a closed radial 
cell. The closed radial cell is an archaic character and is found only in a 



1907.] Wheeler, Fungus-growing Ants uf North America. 795 

few Myrmiclne genera, such as Cryptocerus, Atofomyrmex, Myrmecina, 
Pheidologeton, Aeromyrma, Carebara, Lophomyrmex and certain species 
of Tetramorium. In my opinion no great taxonomic importance is to be 
attached to this character; nevertheless its constant occurrence in the true 
Attini must be taken into consideration." 

In a later paper (1895) Emery groups the genera above mentioned as 
follows : 

Tribe Dacetii: Daceton, Acanthognathus, Orectognathus, Strumigenys, 
Epitritus, Rhopalothrix, Ceratobasis. 

Tribe Attii: embracing besides the genera and subgenera enumerated 
in the introduction to this paper, Wasmannia and possibly also Ochetomyr- 
mex. 

Tribe Cryptocerii: Procryptocerus and Cryptocerus. 
Tribe. Cataulacii: Cataulacus. 

Emery is apparently of the opinion that the Attii are related to the 
Tetramorii through such intermediate genera as Wasmannia and Ocheto- 
myrmex, whereas Forel is inclined to seek their origin among the Dacetonii 
through such a series of genera as Cyphomyrmex, Rhopalothrix and Strumi- 
genys. Morphological considerations may be adduced in support of either 
of these contentions. The question then naturally arises as to whether there 
are in the Dacetonii or Tetramorii any ethological peculiarities which by 
further development could lead to the highly specialized fungus-growing 
habits of the Attii. 

Forel (1902) regards Cyphomyrmex as the most primitive genus of Attii 
and believes that some of the species do not raise fungi, whereas the others 
make very imperfect gardens on insect excrement. These ants would thus 
be transitional in their habits to the Dacetonii, many of which also live in 
damp places in rotten wood, where fungi grow in abundance and where 
there is plenty of insect excrement that might gradually come to be em- 
ployed as a substratum. In an earlier pajier (1893) Forel quotes in support 
of his view an observation of H. Smith on the West Indian Strumigenys 
smithi Forel, a species which nests in rotten wood. Smith says that "the 
cavities in which these ants are found are always black inside, as if with some 
fungoid growth." Forel infers from this that some species of Strumigenys 
cultivate fungi. It seems to me, however, that his view evaporates into a 
mere hypothesis when the facts arc more closely scrutinized. In the first 
place, there is no known species of Cyphomyrmex, nor in fact any Attiine 
ant, which does not cultivate fungi. I have shown in the third part of the 
present paper that statements to the contrary in regard to C. rimosus are 
false and due to superficial observations. In the second place, there is not 
a particle of evidence to prove that the Dacetonii cultivate fungi. The 



796 Bulletin American Museum of Natural History. [Vol. XXIII, 

species discovered by Smith may have been nesting in the abandoned fungus- 
stained galleries of ambrosia beetles, or the dark color of the walls rnay 
• have been due to other causes. I may say also that in no colonies of the 
various species of Strumigenys which I have found in the United States and 
West Indies were there any traces of fungi. These ants live in rather small 
communities under .stones or in rotten wood and feed on insects. Many of 
our species live as thief ants, after the manner of Soleno'psis molestd Say, 
in the nests of larger, ants. Rhopalothrix seems to have similar habits, to 
judge from some field notes accompanying a colony of an undescribed species 
taken, with all its larvae and pupse, under a stone in Jamaica. 

Ford's view, however, contains an interesting suggestion, for the nature 
of the substratum on which the fungi are grown may be supposed to throw 
some light on the origin of the habit under discussion. In all the fungicolous 
insects there is an vmmistakable tendency to' employ vegetable substances 
that have passed through the alimentary tract of insects. This is the case in 
all fungus-growing termites, and in the ambrosia beetles. Among the Attii, 
as I have shown, this tendency is apparent in nearly all the species that have 
been closely observed. Though most pronounced in the lower genera and 
subgenera (Cyphomyrmex, Apterostigma, Mycocepurus, Trachymyrmex) , it 
is not wholly lost even in the leaf-cutting Attw, and the method employed 
by the Atta queens in manuring their incipient fungus-gardens suggests that ■ 
the food plant may haxe been originally grown on fecal substances. It is 
quite possible, however, that in the Attii this habit is secondary and that it 
was preceded phylogenetically by culture on some other substance since 
generally abandoned as less suited to the purpose. This leads us to a con- 
sideration of another view on the origin of the fungus-growing habit. 

Von Ihering (1894) advances the following opinion: . "We know quite 
a number of ants, like the species of Pheidole, Pogonomyrmex and further- 
more species of Aphwnogaster and even of Lasius, which carry in grain and 
seeds to be stored as food. Such grain carried in while still, unripe, would 
necessarily mould and the ants feeding upon it would eat portions of the 
fungus. In doing this they might easily come to prefer the fungi to the seeds., 
If Atta lundi still garners grass seeds and in even greater than the natural 
proportion to the grass- blades, this can only be regarded as a custom which 
has survived from a previous cultural stage." Thus von Ihering would 
explain the origin of fungus cultivation and the supervention of the leaf- 
cutting habit. 

This view, like ForeFs, is, of course, purely hypothetical. There are, 
however, a few facts which indicate that the Attii may have developed from 
grain-storing species allied to the Tetramorii (Meranophis and Tetramoriiim) 
as Emery has suggested. That certain harvesting species form nests and. 



1907.] Wheeler, Fungus-growing Ants of North America. 797 

have many peculiarities of behavior similar to those of the smaller Attii 
is shown by Santschi's observations on Oxyopomyrmex santschii Forel of 
the Tunisian deserts. In a letter to Forel, Santschi states that the nests of 
this ant are "so characteristic that when one has once seen one of them, 
nothing is easier than to find others. I am surprised to find that they have • 
not attracted the attention of other observers. Especially remarkable is 
the tiny crater, which has the form of a cone, hardly more than 4-5 cm. in 
diameter and 2.5-3 cm. high. The circumference of its funnel-shaped top 
is 3-4 cm. across and its margin is always perfectly circular and iCntire, ex- 
cept in nests in process of construction, where it is at first semilunar like the 
very small nests of Messor arenarius. At the bottom of the funnel the small 
entrance is found, 1—2 mm. in diameter, just large enough to permit one of 
the workers to pass. A single nest has rarely two entrances and two cones. 
A single perpendicular gallery descends below the surface. A first chamber 
is found at a depth of 2-3 cm. It is horizontal, attaining a length of 5 cm., 
a breadth of 1 cm. and a height of 5 cm. In this first chamber the pupse 
are kept for the purpose of enjoying the warmth and here I have found a 
number of workers and winged females. Thence the gallery continues to 
descend to a depth of 15-20 cm. and finally opens into two or three chambers 
of the same dimensions as the first. These contain pupse and an ample 
provision of very small seeds. This ant is therefore granivorous. I sur- 
prised a few of the workers entering the nest with seeds in their mandibles. 
They go out foraging singly and not in files like Messor and other genera. 
They are very slow in their movements and are very apt to stop motion- 
less at the least alarm. Day or night one or two of the workers may be 
seen on the outer surface of the crater scarcely moving unless molested, but 
when disturbed they hurriedly retreat into the nest to spread the alarm. 
Their habits are rather nocturnal. If a light is brought near the nest when 
a worker is on the point of leaving it with a grain of sand she hurriedly backs 
into the entrance and there stops, closing it perfectly with her burden. 
If the observer remains very quiet, she eventually comes forth, and deposits 
her load on the slope of the crater. There are scarcely more than thirty 
individuals in a nest." 

Although Oxyopomyrmex has no close taxonomic relations with the Attii 
or Tetramorii, but rather, with members of the complex genus Stenamma, 
it closely resembles Trachymynnex turrijex and Mycetosoritis hartmanni 
in the small size of its colonies, the slowness of its movements and the struc- 
ture of its nests. These resemblances are in all probability; due to conver- 
gent development. Nevertheless, species with habits like Oxyopomyrmex 
might conceivably become f ungicolous by some such substitution of instincts 
as that suggested by von Ihering. So many assumptions, however, would 



798 Bulletin American Museum of Natural History. [Vol. XXIII, 

have to be made in order to account for the dehcate and intricate adaptations 
shown by existing Attii in the cultivation of their fungi, that further specu- 
lation seems idle till we are in possession of a greater body of careful observa- 
vations. 

Less hypothetical and worthier of confidence are the views of Forel and 
von Ihering concerning phylogenetic development within the narrow con- 
fines of the Aftiine tribe itself. But here, too, we must proceed with caution. 
The ants of the genera and subgenera Cyphomyrmex, Myrmicocrypta, 
Sericomyrmex, Apterostigma, Mycocepurus and Mycetosoritis' on the one 
hand, are obviously primitive, for they form small colonies and have mono- 
morphic workers and proportionally small males and females. On the 
other hand, Atta s. str. would seem to be the most recent and highly special- 
ized genus of the tribe, because the colonies are very populous, the workers 
are polymorphic with marked division of labor, and the males and females 
are very large. Between these two groups, Trachymyrmex, Acromyrmex 
and MosUerius occupy an intermediate position. Moeller and subsequent 
writers have been inclined to find a parallel development in the instincts, 
, but this is not so clear as the morphological sequence and relations of the 
various genera and subgenera, for we find Atta s. str. and Acromyrmex 
building gardens on the floors of their chambers like Cyphomyrmex, whereas 
Apterostigma has highly specialized gardens, suspended and enveloped in a 
mycelial web not known to occur in any other Attii. Moreover, at least one 
species of Cyphomyrmex (rimosus) and a species of Atta s. lat. {Mycocepurus 
smithi) cultivate a very different fungus from that known to occur in the nests 
oi any other species; C. wheeleri does not, at least as a rule, use caterpillar 
excrement as a substratum but only small plant slivers; Mycetosoritis special- ■ 
izes to the extent of using only the anthers of flowers, and Sericomyrmex 
opacus has a predilection for fruit pulp. All of these species are therefore 
aberrant in their habits, though belonging to primitive genera. Moeller 
has certainly overestimated the primitive nature of the treatment bestowed 
on the fungi, in the nests of Cyphomyrmex as a group, and although the 
bromatia of the Apterostigma gardens may be of a generalized type, this 
genus is in riiany other respects more highly specialized than Atta s. str. 

Granting the cogency of these considerations, it still remains true that 
the Attii in general present a series of increasingly specialized forms as we 
pass from the species of Cyphomyrmex through the subgenera Mycetosoritis, 
Trachymyrmex, Acromyrmex and Mallerius to Atta s. str. in which we see 
the culmination of a wonderful progress in adaptation. These insects in 
the fierce struggle for existence, everywhere apparent in the tropics, have de- 
veloped a complex of instinctive activities which enables them to draw upon an 
ever-present, inexhaustible food-supply through utilizing the foliage of plants 



1907.] Wheeler, Fungus-growing Ants of North America. 799 

as a substratum for the cultivation of edible fungi. No wonder there- 
fore, that, having emancipated themselves from the precarious diet of other 
ants, v?hich subsist on insects, the sweet exudations of plants and the excre- 
ment of phytophthorous Rhynchota, the Attii have become the dominant 
invertebrates of tropical America! 



BIBLIOGRAPHY. 

a. Fungus-grovnng Ants. 

1899. Andr6, Ernest. Les Fourmis Champignonnistes. Extr., Sac. Grayloise 

d' Emul, Ann^e 1899, pp. 3-12. 

1892. Bates, H. W. The Naturalist on the River Amazon. Ed. by Clodd. London, 

1892. First edit. 1863. 

1888. Belt, Thomas. The Naturalist in Nicaragua. 2d ed., London, 1888 

(1st ed. 1874). 
1886. Brent, C. Notes on the fficodomas, or Leaf-cutting Ants of Trinidad. 

Amer. Natur., XX, no. 2, 1886, pp. 123-131, 7 figs. 
1901. Bolivar, I. Un Nuevo Ortoptero Mimiecofilo Attaphila bergi. Com. Mus. 

Nac. Buenos Ayres, I, 1901, pp. 331-336, 1 fig. 

1900. Branner, J. C. Ants as Geologic Agents in the Tropics. Journ. Geol,, 

Chicago, VIII, pp. 151-153, 3 figs. 
1860. Buckley, S. B. The Cutting Ant of Texas (fficodoma mexicana Sm.). 

Proc. Acad. Nat. Sci. Phila., 1860, p. 233; Ann. Mag. Nat. Hist. (3), VI, 

1860, pp. 386-389. 
1886. Chatrian, N. La Fourmi Sauva. Rev. Scientif. (3), XXXVIII, 1886, 

pp. 371-372. 
1653. Cobo, P. Bernabg. Historia del Nuevo Mundo. 1653 (pubUshed in 1892), 

II, pp. 261-266, passim. 
1906. Cook, M. T. Insectos y Enfermedades del Naranjo. Prim. Informe Anual 

de la Estac. Centr. Agronomica de Cuba, Havana, 1906, pp. 149-172. 
1879. Dewitz, H. Insectenmisbildung. Zool. Am., 2 Jahrg., 1879, pp. 134-136, 

1 fig. 
1900. Dominique, J. Fourmis Jardinieres. Bull. Soc. Sci. Nat. Quest. Nantes, 
•X, pp. 163-168, 3 figg. 

1889. Emery, Carlo. Alleanze Difensive tra Piante e Formiche. Nuova Antologia, 

XIX (3), Feb. 1889, 16 pp. 

1890. Emery, Carlo. Voyage de M. E. Simon au Venezuela. Formicides, 1890. 

1893. Emery, Carlo. Formicides de I'Archipel Malais. Rev. Suisse de Zool. et 

Ann. Mus. d'Hist. Nat. Geneve, I, 1893, pp. 187-229, 1 PI. 

1895. Emery, Carlo. Die Gattung Dorylus Fabr. und die systematische Einthei- 
lung der Formiciden. Zool. Jahrb. Abth. f. Syst. VIII, 1895, pp. 685-778, 
4 taf. text-figg. 

1906. Escherich, Karl. Die Ameise. Schilderung ihrer Lebensweise. Braun- 
schweig, Fr. Viehweg u. Sohn, 1906, 232 pp.', 68 figg. 



800 , , Bulletin American Museum of Natural History. [Vol. XXIII, 

1892. Forel, Augusts. Attini und Cryptocerini'. Mitth. schweiz. Ent. Ges., VIII, 

Heft 9, 1892, pp. 14, 15 (of extract). 

1893. Forel, Auguste. Fonnicides de I'Antille St. Vincent. Recoltees par Mons. 

H. H. Smith. Trans. Ent. Soc. London, Deo. 1893, Pt. IV, pp. 333-418. 
1896(a). Forel, Auguste. Die Fauna und die Lebensweise der Ameisen im Kolum- 

bischen Urwald und in den Antillen. ■ Verh. Schweiz. Nat. Ges., 1896, 

pp. 148-150; Extr. Arch. Sci. Physic. Nat. Geneve (4), II, pp. 616, 617. 
1896 (b) . Forel, Auguste. Zur Fauna und Lebensweise der Ameisen im kolumbischen 

Urwald. Mitth. Schweiz. Entom. Ges., IX, Heft 9, 1896, pp. 401-410. 
1896(c). Forel, Auguste. Quelques Particularites de I'Habitat des Fourmis de 

I'Amerique Tropicale._ Ann. Soc. Entom. Belg., XL, pp. 167-171. 

1897. Forel, Auguste. Communication Verbale sur les Mceurs des Fourmis de 

I'Amerique Tropicale. Ann. Soc. Entom. Belg., XLI, pp. 329-332; Extr. 
Feuille Jeun. Nat.' {3), Ann. 23, no. 427, p. 54. 

1898. Forel, Auguste.- La Parabiose chez les Fourmis. Bull. Soc. Vaud. Sci. Nat. 

(4), XXXIV, 1898, pp. 380-384. 

1899-1900(a). Forel, Auguste. Ebauche sur les Mceurs des Fourmis de I'Ame- 
rique du Nord. Rivista di Sci. Biol., no. 3,' II, 1900, 13 pp. Also in part 
in Ann. Soc. Entom. Belg., XLIII, 1899, pp. 438-447. Translation in 
Psyche, IX, 1901, pp. 231-239, 243-245. 

1899-1900(b). Forel, Auguste. Biblogia Centrali- Americana. Hymenoptera III. 
Formicida?, 1899-1900, pp. 169, 4 pU. 

1901. Forel, Auguste. Fourmis Termitophages, Lestobiose, Atta tardigrada, 

Sousgenres d'Euponera. , Ann. Soc. Entom. Belg., XLV, 1901, pp. 389-398. 

1902. Forel, Auguste. Beispiele phylogenetiseher Wirkungen 'und Riickwirkungen 

bei den Instinkten und dem Kbrperbau der Ameisen als Belege fur die 

Evolutionslehre und die psychophysische Identitatslehre. Journ. f. 

Psychol, u. Neurol, I, 1902, pp. 99-110. 
1905. Forel, Auguste. Einige biologische Beobachtungen des Herrn Prof. Dr. 

Goldi an brasilianischen Ameisen. Biol. Centralbl., XXV, 1905, pp. 170- 

181, 7 figg. 
1894. Gibson,. R. J: H. The Mushroom Beds of the South American Ants. Proc. 

Liverpool Lit. Soc, XLVIII, 1894, pp. 9,9-105. 
1905(a). Goeldi, E. Beobachtungen tiber die erste Anlage einer neuen Kolonie 

von Atta oephalotes. C. R. Sme Congr. Internat. Zool.- Berne, 1905, pp. 

457, 458. 
1905(b). Gceldi, E. Myrmecologische Mittheilung das Wachsen des Pilzgartens 

bei Atta cephalotes betreffend. Ibid., pp. 508-509. 
1905. Huber, ■ Jakob. Ueber die Koloniengrilndung bei Atta sexdens. Biol. 

Centralbl, XXV, pp. 606-619, 625-635, 26 figg. 
1882. von Ihering, H. Ueber Schichtenbildung durch Ameisen (Atta cephalotes). 

Briefl. Mitth. aus Mundoro, Rio Grande do Sul, Brasilien, Oct. 1881. 

Neues Jahrb. Mineral, 1882, I, pp. 156, 157. 
1894. von Ihering, H. Die Ameisen von Rio Grande do Sul. Berl Entom. Zeitschr., 

XXXIX, 1894, pp. 321-446, 1 pi., text figg. 
1898. . von Ihering, H. Die Anlage neuer Colonien und Pilzgarten bei Atta sexdens. 

Zool. Anzeig., 21 Jahrg., 1898, pp. 238-245, 1 fig. 
1900. Lagerheim, 6. Ueber Lasius fuliginosus (Latr.) und seine Pilzzucht. 

Entom. Tidskr., Arg. 21, 1900, pp. 17-29. 



1907.] Wheeler, Fungus-growing. Ants of North America. 801 

1901. Ledebur, A. Ueber Pilze ziichtende Ameisen. Nerthus, Jahrg. 3, pp. 411- 

414, 422-425. 
1867. Lincecum. G. The Cutting Ant of Texas (CEcodoma Texana). Proc. 

Acad. Nat. Sci. Phila., 1867, pp. 24-31. 
1831. Lund, A. W. Lettre sur les Habitudes de quelques Fourmis du Br6si]; 

addressee a M. Audouin. Ann. Sci. Nat., XXIII, 1831, pp. 113-138. 
1771. Merian, Mme. M. S. Histoire Generale des Insectes de Surinam et de toute 

I'Europe. Paris, L. C. Desnos, 1771. 

1879. McCook, H. C. On the Architecture and Habits of the Cutting Ant of Texas 

(Atta fervens). Proc. Acad. Nat. Sci. Phila., Feb. 11, 1879, pp. 33-40: 
Ann. Mag. Nat. Hist. (5), III, 1879, pp. 442-449. 

1880. McCook, H. C. Note on a New Northern Cutting Ant, Atta septentrionalis. 

Proc. Acad. Nat. Sci. Phila., 1880, pp. 359, 360, 1 fig. 
1888. McCook, H. C. Note on the Sense of Direction in a European Ant (Formica 
' rufa). Ann. Mag. Nat. Hist. (6), II, 1888, pp. 189-192. 

1902. McCook, H. C. Tenants of an Old Farm. Philadelphia, Geo. W. Jacobs 

& Co., pp. 230-276, first ed. 1884. 

1893. Moeller, A. Die Pilzgarten einiger sudamerikanischer Ameisen. Heft 

VI, Schimper's Botanische Mitth. aus d. Tropen, 1893, 127 pp. 7 pis. 
1900. Moreno, A. Observaciones acerca de las Costumbres de las Hormigas. 

Mem. Rev. Soc. Cient. Antonio Alzate/XIY, 1900 Rev. pp. 60-62. 
1881.' Morris, G. K. A New Leaf-cutting Ant. Amer. Natur., Feb. 1881, pp. 

100-102. 
1874. MlUler, Fritz. The Habits of Various Insects. (Letter to Chas. Darwin.) 

Nature, June 11, 1874, pp. 102, 103. 

1883. Muller, Fritz. [Article on Atta]. Blumenauer Zeitung, 1883. 

1884. Nehriing, H. [On Atta texana]. Zool. Garten,- XXV, 1884, p. 265. 

1535. de Oviedo y Valdez, G. F. Historia General de las Indias. I, lib. XV, cap. 1. 
1844. Relche, L. Note sur les Propriet^s Lumineuses de Pyrophorus, Nyctophanes, 
et sur le bruit fait par les Passalus; Oecodoma cephalotes. Ann. Soc. 
, Entom. France, (2), II, 1844, Bull. pp. 63-67. 

1894. Sampaio de Azevedo, A. G. Saiiva ou Manhiiadra. Monographia. Sao 

Paulo, 1894. 
1896(a). Schenckling-Prgrot. Ameisen als Pilzziichter und esser. Illustr. Wochen- 

schr. f. Entom., 1 Jahrb., no. 6, 1896, pp. 89-93. 
1896(b). Schenckling-Prevot. Die Pilzgarten der Haarameisen. Insektenborse, 

13 Jahrg., 1896, pp.' 153, 154. 
1896(c). Schenckling-PrSvot. Die Hockerameisen und ihre Pilzgarten. Ibid. 

p. 264. 
1897. Schenckling-Pr^vot. Rozites gongylophora, die Kulturpflanze der Blatt- 

schneide-Ameisen. Illustr. Wochenschr. f. Entom., 2 Jahrg., 1897, pp. 56- 

60. ■ 

1888. Schimper, A. P. W. Die Wechselbeziehungen zwischen Pflanzen und 

Ameisen im tropischen Amerika. Botan. Mitth. aus den Tropen, Heft 

1, 1888, 95 pp. 3 pi. 
1734-1735. Seba, Albertus. Looupletissimi Rerum Naturalium Thesauri Acourata 

Descriptio 4 voL, fol., Amstelodami, 1734-1735. 

[Sept., 1907.] 



802 Bulletin American Museum of Natural History. [Vol. XXIII, 

1894. Spencer, Herbert. Origin of Classes among the "Parasol" Ants. Nature, 

LI, 1894, pp. 12.5, 126. . 

1896. Swingle, W. T. Fungus Gardens in the Nest of an Ant (Atta tardigrada 

Buokl.) near Washington. Proc. Am. Assoc. Adv. Sci., 44th Meet., 1896, 

pp. 185, 186. 
1892(a). Tanner, J. E. OLcodoma cephalotes. The Parasol or Leaf-cutting 

Ant. Trinidad Field Nat. Club, I, no. 3, Aug. ,1892, pp. 68, 69. 
1892(b). Tanner, J. E. fficodoma cephalotes. Second, Paper, Ibid., no. 5. Dec. 

1892, pp. 123, 127. 
1870. Townsend, B. R. The Red Ant of Texas, Amer. Entomol. and Botan., St. 

Louis, Mo., Oct. II, 1870, no. 11, pp. 324-325. . 
1895(a). Urich, F. W. Notes on Some Fungus-growing Ants in Trinidad. Journ. 

Trinidad Club, II, no. 7, 1895, pp. 175-182. 
1895(b). Urich, F. W. Notes on the Fungus-growing and eating Habit of Seri- 

comyrmex opacus Mayr. Trans. Entom.. Soc. London, 1895, pp. 77, 78. 

1894. Wasmann, Erich. Kritisohes Verzeichnis der myrmekophilen und termito- 

philen Arthropoden. Berlin, Felix Dames, 1894. . 

1895. Wasmann, Erich. Die Ameisen- und Termitengaste von Brasilien. Verh. 

h. k. Zool. Bot. Ges. Wien, 1895, pp. 2-46. 
1900. Wasmann, Erich. The Guests of Ants and Termites. Entom. Record and 
Journ. of Variat., XII, 1900, 15 pp. pi. iii. 

1900. Wheeler, W. M. A New Myrmecophile from the Mushroom-Gardens of the 

Texan Leaf-cutting Ant. Amer. Natur., XXXIV, 1900, pp. 851-862, 6 figg. 

1901. Wheeler, W. M. Biological Notes on Mexican Ants. Ann. Soc. Entom. 

Belg., XLV, 1901, pp. 199-205. 
1903. Wheeler, W. M. The Origin of Female and Worker Ants from the Eggs of 

Parthenogenetic Workers. Science, N. S., XVIII, 1903, pp. 830-833. 
1905(a). Wheeler, W. M. The Ants of the Bahamas, with a List of the Known 

West Indian Species. Bull. Amer. Mus. Nat. Hist., XXI, 1905, pp. 79- 

135, pi. vii, text-figg. 
1905(b). Wheeler, W. M. An Annotated List of the Ants of New Jersey. Ibid., 

pp. 371-403. 
1906(a). Wheeler, W. M. The Queen Ant as a Psychological study. Popul. Sci. 

Month., Apr. 1906, pp. 291-299, 7 figg. Reprinted in Scientif. Amer., 

Suppl. no. 1603, Sept. 22, 1906, pp. 25685, 25686. 
1906(b). Wheeler, W. M. On the Founding of Colonies by Queen Ants, with 

Special Reference to the Slave-making Species. Bull. Amer. Mus. Nat. 

Hist., XXII, 1906, pp. 33-105, pis. viii-xiv, 1 text-fig. 
1882. White. [Great Swarms of Oecodomas in the Parand] in "Cameos from the 

Silver Land," II, 1882, pp. 437, 438. 
1885. Will, F. Die Geschmacksorgane der Insekten. Zeitschr. f. wiss. Zool., XLII, 

1885, pp. 674-707, Taf. XXVII.. 
1899. Anonymous. Tropische Ameisen als Pilzzuchter. Natur, 48 Jahrg., 1899, 

pp. 135-137. 

h. Fungus-growing Termites. 

1905. Doflein, F. Die Pilzkulturen der Tenniten. Verh. deutsch. zool. Ges., 15. 
Vers. pp. 140-149, 2 figg. 



1907.] Wheeler, Fungus-growing Ants of North America. 803 

1906. Doflein, F. Ostasienfahrt. Erlebnisse und Beobachtungen eines Naturfor- 

schers in China, Japan und Ceylon. B. G. Teubner, Berlin, 1906, pp. 
454-473, figg. 

1900. Errington de la Croix, Mme. Observations sur le Termes carbonarius Havi- 

land. Bull. Mus. Hist. Nat. Paris, 1900, pp. 22, 23, 1 fig. 
1855-1860. Hagen, H. Monographie der Termiten. Lmn. Entomol., X, 1855, 
pp. 1-144, 270-325; XII, 1858, pp. 1-342, Taf. i-iii; XIV, 1860, pp. 73- 
128. 

1907. Harris, J. A. The Fungi of Tennite Nests. Amer. Natur:, XLI, 1907, 

pp. 536-539. 

1898. Haviland, 6. D. Observations on Termites, or White Ants. Journ. Linn. 

Soc. Zool., XXVI, 1898, pp. 358-442, pi. xxii-xxv, 2 text-figg.; reprinted 
in Ann. Rep. Smithson. Instit., 1901, pp. 667-678, 4 pis. 

1899. Holtermann, Carl. Pilzbauende Termiten. Botan. Untersuch. (Festschr. 

f.,Schwendener), 1899 pp. 411-420, 1 fig. 

1901. Karawaiew W. Supplement to the Preliminary Account of an Excursion 

to the Island of Java. (In Russian.) Mem. Soc. Natural. Kiew, XVII, 
Livr. 1, 1901, pp. 298-303, 1 pi. , 

1899. Knuth, Paul. Termiten und ihre Pilzgarten. Illustr. Zeitschr. f. Entom., IV, 

1899, pp. 257-259, 4 figg, 
1779. Konig J. G. Naturgeschichte der sogenannten weissen Ameise. Beschaft. 

Berl. Ges. naturforsch. Freunde, IV, 1779, pp. 1-28, Taf. i. 
1906. Fetch, T. The Fungi of Certain Termite Nests. (Termes redemanni 

Wasm.; and T. obscuriceps Wasm.) Ann. Koy. Bot. Gard. Peradeniya, 

III, 1906, pp. 185-270, PI. V-XXI. 
1903. Silvestri, F. Contribuzione alia Conoscenza dei Termitidi e Termitofili. 

Redia, 1, 1903, pp. 1-234, Taf. i-vi, 57 text-figg. , 
1806. Sjostedt, Y. Termes hlljeborgi, eine neue wahrsoheinlich pilzanbauende 

Tagtermite aus Kamerun. Festschr. f. W. Lilljeborg. 1896, pp. 267- 

280, 1 Taf. 

1900. Sjostedt, Y. Monographie der Termiten Afrikas. Kongl. Svenska Vetensk. 

Akad. Handl, XXXIV, no. 4, Apr. 11, 1900, 236 pp. 9 pi. 

1903. Sjostedt, Y. , Termiternaochderas Biologi. Ihid., Arsbok, 1903, pp. 89-101. 

1904. Sjostedt, Y. Monographie der Termiten Afrikas. Nachtrag. Ihid., 

XXXVIII, no. 4, 1904, pp. 1-120, 4 pi. 
1781. Smeathman, Henry. Of the Termites in Africa and Other Hot Climates. 

Phil. Trans. Roy. Soc. London, LXXI, 1781, pp. 60-85, 2 pi. 
18S6. Smith, E. F. ■ White Ants as Cultivators of Fungi. Amer. Natur., XXX, 

ISee, pp. 319-321. ■ ■ 

1904. Tragardh, I. Termiten aus dem Sudan. Results Swed. Zool. Exped. to 

Egypt and the White Nile (1901), Pt. I, 1904, pp. 1-47, 3 pi. 8 text-figg. 

c. Ambrosia Beetles. 

1872-1875. Altum, B. Forstzoologie. Berlin, 1872-1875. 

1873. Beling. Beitrag zur Naturgeschichte des Bostrychus lineatus und des 

Bostrychus domesticus. Tharander Jahrb. XXXIII, 1873, pp. 17-44. 
1899. Eggers, H. Zur Lebensweise des Xyleborus cryptographus Ratz. Illustr. 

Zeitschr. j. Entom., IV, 1899, pp. 291-292, fig. 



804 Bulletin American Museum of Natural History. [Vol. XXIII. 

1881. EichhofE, W. Die Europaischen Borkenkafer. Berlin, J. Springer, 1881, 
pp. 280-281. 

1906. ■ Felt, E. P. Insects Affecting Park and Woodland Trees. N. Y. State 

Museum, Mem. 8, Albany, N. Y. 1906. pp. 369-396. 
1895. Gbthe,. R. Berioht d. k. Lehranst. f. Obst- Wein-u. Gai'tenbau zu Geisen- 
heim (1894-95), 1895, p. 25. 

1907. Hagedorn. Pilzziichtende Borkenkafer. Naturwiss. Wochenschr., Neue 

Folge, 6. Bd. No. 19. 12 Mai, 1907, pp. 289-293, 12 figg. 
1844. Hartig, T. AUgem. Forst-u. Jagtzeitg. B. XIII, 1844, pp. 73, 74. 
1872a. Hartig, T. Der Fichtensplintkafer Bostrichus (Xyloterus) lineatus. 

Ibid., XLVIII, 1872, pp. 181-183. 
1872b. Hartig, T. Der Buchensplintkafer Bostrichus (Xyloterus) domesticus. 

ibid., XLVIII, 1872, pp. 183-184. 
1906. Hedgcock, G. G. Studies upon Some Chromogenic Fungi which Discolor 

Wood. Seventeenth Ann. Rep. Missouri Boi. Garden, 1906, .pp. 59-114, 

pis. iii-xii. 

1898. Hopkins, A. D. On the History and Habits of the "Wood Engraver" 

Ambrosia Beetle — Xyleborus xylographus (Say), Xyleborus saxeseni 
(Ratz.) — with Brief Descriptions of Different Stages. Canad. Entom., ' 
XXX, 1898, pp. 21-29, 2 pis. 

1899. Hopkins, A. D. Report on Investigations to Determine the Cause of Un- 

healthy Conditions of the Spruce and Pine from 1880-1893. Bull. 56 

West Virginia Agrie. Exper. Sta., April, 1899. 
1904(a). Hopkins,' A. D. Insect Injuries to Hardwood Forest Trees. Yearbook 

U. S. Depart. Agric. 1903, Washington, 1904, pp. 313-328, pi. xxxix, 

17 text-figg. 
1904(b). Hopkins, A. D. Catalogue of Exhibits of Insect Enemies of Forests 
' and Forest Products at the Louisiana Purchase Exposition, St. Louis, 

Mo., 1904, Washington, 1904, pp. 15, 16. . 

1905. Hopkins, A.. D. Insect In,iuries to Forest Products. Year-book U. S. 

Dep. Agric. 1904, Washington, 1905, pp. 381-398, 14 figg. 
1897(a). Hubbard, H. G. The Ambrosia Beetles of the United States. Bull. no. 

7, n. s. Dep. Agric. Div. Entom. 1897, pp. 11-30, 34 figg. 
1897(b). Hubbard, H. G. Ambrosia Beetles. Yearbook U. S. Dep. Agric. 1906, 

pp. 421-430, Washington, 1897, 7 figg. 

1906. Leisewitz, W. Ueber chitinose Fortbewegungs Apparate einiger (insbeson- 

dere fussloser) Inselttenlarven. Miinchen, E. Reinhardt, 1906, 143 pp. 
46 figg. 
1839-1844. Ratzeburg, J. T. Die Forstinsekten. 3 vol., Berlin, Nicolai'sohe 
Buchhandl, 1839-1844. '. . ' 

1895. Ratzeburg, J, T. Lehrbuch der Mitteleuropaischen Forstinsektenkunde. 

8 Aufl. Vienna, Ed. Holzel, Bd. I, 1895. 
1836. Schmidberger. Beitriige zur Obstbaumzucht und zur Naturgeschichte der 

den Obstbaumen schadliohen Insecten. Heft. IV, Linz, 1836. 
1903. von Schrenk, H. The " Bluing " and the " Red Rot " of the Western Yellow 

Pine, with Special Reference to the Black Hills Forest Reserve, U. S. 

■Dep. Agric. Bur. Plant Indust. Bull. No. 26. Washington, 1903, 40 

pp. 14 pll. 

1896. Smith, E. T. Ambrosia. Amer. jVoi!., XXX, 1896, pp. 318, 319.' ?■ 



1907.] Wheeler, Fimgus-growing Ants of North America. 805 



EXPLANATION OF THE PLATES. 

Plate XLIX. 

Fig. 1. — Cyphomyrmex rimosus Spinola var. comalensis var. nov. Worker. 

Fig. 2. — Cyphomyrmex wheeleri Forel. Worker. 

Fig. 3. — Atta (Trachymyrmex) turrifex Wheeler. Worker. 

Fig. 4.^- Atta (Trachymyrmex) septentrionalis McCook. Worker. 

Fig. 5. — Atta (Moellerius) versicolor Pergande. Worker. 

Fig. 6. — Atta (Mycetosoritis) hartmanni sp. nov. Worker. 

Fig. 7. — The same in profile. 

Fig. 8. — A. (M.) hartmanni sp. nov. Male. 

Fig. 9. — Atta (Trachymyrmex) arizonensis sp. nov. Dealated female in profile. 

Fig. 10. — Head of same from above. 

Fig. 11. — Atta texana Buckley. Soldier. 

Fig. 12. — Thorax of same in profile. 

Fig. 13. — Atta texana. Media. 

Fig. 14. — Atta texana. Minima. 

-Pl.ite L. 

Fig. 15. — Atta (Mycocepurus) smithi Forel. Worker. 

Fig. 16. — Same in profile. 

Fig. 17. — Sericomyrmex opacus Mayr. Worker. 

Fig. 18. — Myrmicocrypta brittoni sp. nov. Worker. 

Fig. 19. — Same in profile. 

Fig. 20. — Apterostigma pilosum. Mayr. Worker. 

Fig. 21. Atta sexdens L. Brazil. Hypopygium of male. 

Fig. 22. — Atta cephalotes L. Panama. Hypopygium of male. 

Fig. 23. — Atta insularis Guerin. Cuba. Hypopygium of male. 

Fig. 24. — Atta texana Buckley. Texas. Hypopygium of male. 

Fig. 25. — Atta mexicana F. Smith. Mexico. Hypopygium of male. 

Fig. 26. — Atta (Moellerius) versicolor Pergande. Male. Genitalia from above. 

Fig. 27. — Unusual triple nest-entrance of Trachymyrmex turrifex. 

Fig. 28. — Unusual double nest-entrance of Mycetosoritis hartmanni. 

Fig. 29. — Bromatia of fungus (Tyridiomyces formicarum gen. et sp. nov.), 
cultivated and eaten by Cyphomyrmex rimosus and its various subspecies and varie- 
ties. 

Plate LI. 



Fig. 30. — Nest diagram of Mycetosoritis hartmanni (Nest X of the table on p. 
763), showing four chambers, the connecting galleries, and the pendent fungus 
gardens. 

Fig. 31. — Nest diagram of M.. hartmanni (Nest T of the table on p. 763), with 
three chambers all containing fungus gardens. 

Fig. 32. — Nest diagram of M. hartmanni (Nest U of the table on p. 763), with 
three chambers. 



806 Bulletin American Museum of Natural History. [Vol. XXIII, 

Fig. 33. — Nest diagram of Trachymyrmex turrifex (Nest L of the diagram on 
p. 756), with five well-developed chambers and pendent fungus gardens in all but the 
first. _ 

Fig. 34. — Nest diagram of T. turrifex (Nest N of the table on ]). 756), with four 
chambers, the lowermost small, recently excavated, and with an incipient garden 
suspended from rootlets. 

Fig. 35. — Nest diagram of T. turrifex (Nest of the table on ]i. 756), with four 
well-developed chambers and flourishing gardens in three of them. 

Fig. 36. — Nest diagram of T. turrifex (Nest P of the table on p. 756), with five 
chambers and poorly developed fungus gardens in three of them. This nest shows 
very clearly the suspension of the substratum from the rootlets hanging into or 
traversing the chambers. 

Fig. 37. — Nest diagram of Trachymyrmex septentrionalis var. obscurior (Nest C 
of the table on p. 749), consisting of only two chambers, both containing pendent 
fungus gardens. 

Fig. 38. — Nest diagram of T. obscurior (Nest D of the table on p. 749), consisting 
of three chambers two of which open directly into each other. The mound of 
sand is shown in the typical position in front of the oblique entrance galleiy. The 
first chamber contains exhausted substratum ready to be carried oiit of the nest. 

Plate LII. 

Fig. 39. — Nest diagram of Trachymyrmex obscurior (Nest I of the table on p. 
749), of the racemose type, with five chambers. Extending from the single chamber 
on the right is an unfinished gallery. All the chambers contain well-developed 
pendent gardens except the first, which is partially filled with exhausted substratum. 

Fig. 40. — Nest diagram of T. obscurior (Nest J of the table on p. 749) of the 
racemose type, with seven chambers, six of which are of large size. Of the latter, 
five contain flourishing gardens but one (to the extreme right) seems to have been 
only recently excavated by the ants. The crater of this nest was best developed 
behind the entrance. 

Fig. 41. — Nest diagram of .T. obscurior (Nest G of the table on p. 749) of the 
racemose and horizontally spreading type, with four chambers. The first chamber, 
in which the mother queen established her colony, had been subsequently enlarged 
by the workers. 

Fig. 42. — Nest diagram of T. obscurior (Nest H of the table on p. 749) of the 
racemose type, with four chambers. As in the preceding, the first chamber had . 
been enlarged by the workers, the lowermost was apparently in pi-ocess of excava- 
tion. 

Fig. 43. — Cells composing the bromatia of Tyridiomyces formicarum, the pecu- 
liar fungus grown by Cyphomyrmex rimosus. 

Fig. 44. — Cells composing the bromatia of the same or an allied species of 
Tyridiomyces grown by Mycocepurus smithi var. borinquenensis . 

Plate LIII. 

Fig. 45. — Nest diagram of Trachymyrmex obscurior (Nest F of the table on p. 
749), resembling the nests of T. turrifex, with five chambers. 



1907.] Wheeler, Fungus-growing Ants of North America. 807 

Fig. 46.^- Nest diagram of Trachymyrmex turrifex (Nest R of the table on p. 
756) in pure sand, showing the elongation of the galleries. 

Fig. 46a. — Deeper portion of the same nest with incipient gardens on the root- 
lets traversing the two lower chambers. 

Fig. 47. — Attaphila fungicola Wheeler. Male. From nest of Atta texana. 

Fig. 48. — A. fungicola. Female; dorsal view. 

Fig. 49. — Same, ventral view. 

Fig. 50. — Attaphila bergi Bolivar. Male, from nest of Acromyrmyx lundi. 
(After Bolivar.) 

Fig. 51. — A. bergi, Female. (After Bolivar.) 

Fig. 52, — Head of same. (After Bolivar.) 

Fig. 53. — Hypopygium of same. (After Bolivar.) 

Fig. 54. — A. bergi. — Hypopygium of male. (After Bolivar.) 

Fig. 55. — Fungus garden of Termes bellicosus Smeathm. (After Smeathman.) 

Fig. 56. — ^^Bromatia of saine more highly magnified. (After Smeathman.) 

Fig. 57. — Portion of the fungus garden of a Malayan Termes, showing spherical 
bromatia of Agaricus rajap Holtermann. (After Karawaiew.) Natural size. 

Fig. 58. — Bromatium from the fungus garden of an African Termite, Termes 
vulgaris Havil. (After Tragardh.) 

Fig. 59. — Portion of same crushed under a cover-glass and more highly magni- 
fied, to show the component cells. (After Tragardh.) 

Fig. 60. — - A fungus garden of the African Eutermes Jieterodon Sjost. |- natural 
size. (After Sjostedt.) 

Fig. 61. — Section of same. (After Sjostedt.) 

Fig. 62. — Ambrosia beetle {Xyleborus celsus Eiohh.) of the hickory. Female, 
enlarged. (After Hubbard.) 

Fig. 63.— X. celsus, Male. (After Hubbard.) 

Fig. 64. — Piece of hickory showing burrows of X. celsus in the sapwood. (After 
Hopkins.) 

Fig. 65. — "Ambrosia" or fungus grown by X. celsus enlarged. On the right 
a few of the filaments more highly magnified. 



TflT.l.ETlN- A. M. N. II. 



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FuNGUS-GItOVVI.Nli AxTS OF Nolfl'll Amkiucv 



Bulletin A. M. N. 11. 



Vol.. XXIII, Pj.atk LIII. 




1''iiN(ju.s-l:uu\mm; Ants of Noktu Amekica.